Anyone with Stainless Works exhaust system with the turbo chambered mufflers?

[HAWAIIZR-1]

I thought I had made up my mind about going with the Corsa exhaust system and their black tips option, but looking into the Stainless Works cat back system with turbo chambered mufflers too. I had a chance to hear the system with the more aggressive Turbo S tube mufflers and that is a bit much for me and it has resonance/drone.

http://stainlessworks.net/chevy-zr1-corvette-1990-95-exhausts

SW advertises their system even with X-pipe to not have resonance with the turbo chambered mufflers and the saleperson also confirmed that over the phone. I thought I was going to leave my new to me 95 all stock, but it is way to quiet for me. When I tracked the car at Laguna Seca a few weeks ago I had a video done with 4 cameras and they had one at the mufflers pointing down to record the sound. It sounds like crap and very restricted sounding so stock has to go. I thought about the cut out system, but decided against that.

I would like to have a discussion with someone that has experience with the SW system and turbo chambered mufflers.

Thanks in advance.

[XfireZ51]

So Craig would you be doing away w the resonator and using the SW Xpipe in its place? Understand that SW sells an Xpipe option that comes w a "cheese grater" insert to tame resonance. When I bought mine, that's what they sent me, but my buddy Al removed it because of restriction. Don't know much about the Turbo S muffs since I'm using the Dynomax Ultraflow 3" inlet and dual NPP Z06
tips. Mike100 is using those tips and he may be close to you in CA.

[HAWAIIZR-1]

So Craig would you be doing away w the resonator and using the SW Xpipe in its place? Understand that SW sells an Xpipe option that comes w a "cheese grater" insert to tame resonance. When I bought mine, that's what they sent me, but my buddy Al removed it because of restriction. Don't know much about the Turbo S muffs since I'm using the Dynomax Ultraflow 3" inlet and dual NPP Z06
tips. Mike100 is using those tips and he may be close to you in CA.

Hey Dom,

Yes, I was going to buy the whole system and it comes with the Xpipe. I'm not sure if the Xpipe with this system has the "cheese grater" in it, but I do have a new SW Xpipe that is open in case I need to use it instead. Maybe that is why they are claiming no resonance with the other Xpipe?

I really considered going the route you did and at one time was looking for the NPP parts and using my existing B&B on my 90 to modify with Dynomax mufflers. Since I don't know if I am keep that car or not I thought to make this simple and just get a cat back bolt on system. I just can't grasp the concept of putting on smaller pipes than stock even though I know the 2.5 mandrel bent Corsa flow better than stock due to open system in mufflers. Next Sat I am entered in a local car show and another member will be there for me to hear his Corsas. I might not like the sound of that so looking at other choices.

My thought is go the SW chambered muffler system and if I can't stand the drone/resonance I would mod the tips with NPP and go like others. Thank for your thoughts and I did see Mike100's system that is pretty trick too. I missed the chance to hear more exhaust systems while at BG last month. :cheers:

[XfireZ51]

I'm sorry I couldn't make the Gathering this time around. Life gets in the way sometimes. I have an on-off switch on my NPP which is less sophisticated than Mike's but it works fine for me. Usually ride around w second tip shut off. Use a console switch to open/close whenever I am looking to impress. :dancing

[HAWAIIZR-1]

I'm sorry I couldn't make the Gathering this time around. Life gets in the way sometimes. I have an on-off switch on my NPP which is less sophisticated than Mike's but it works fine for me. Usually ride around w second tip shut off. Use a console switch to open/close whenever I am looking to impress. :dancing

I wish I could have met you there. I know what you mean and my life is back on hold again for another year until I finish this MBA program. I was fortunate to change campus (short break) and had an opportunity to make the Gathering otherwise I would not have.

When I finish school next year I'll have more time to attend to hobbies and playing with these Zs, Lightning truck, and Harley. It can be quite overwhelming trying to mod all of these toys. I think I will probably end up following you guys with the slick NPP controlled set up if I go this SW route. Thanks for your thoughts!

[mike100]

I have had at least 4 different exhaust systems that I can recall. Most of them are loud ;).

I have also ridden in a couple of flowmaster cat-back cars and a borla one with a resonator(just this morning and surprisingly not loud). The flowmaster ones rumbled and droned a bit and both cars had good top end pull.

The newest SW x-pipe does not contain the glasspack cheese grater insert...the mufflers sort of do, but the combined area of the twin outlets is far greater than that of one 3" pipe. The SW with X-pipe sounds just like the B&B and the quality is similar, but the registry does(did?) have that big discount on the SW stuff. The chambered muffs are plenty loud and drone like crazy. Pretty much the majority of C4 exhausts either drone and/or are very loud. I had to put the vacuum flappers on the straight thru part of my SW mufflers to get the 1/4 wave noise cancellation effect. This works really well, except it will still drone in 6th gear below 80 mph. The other gears worked well for me. I ran this system with headers- never with the stock manifolds.

I didn't like the Corsa- you could tell it wasn't quite making the top end the same as the big 3" pipe sets. I would much prefer to build a custom NPP valved turbo muffler on the stock 2.7" pipes before I would run a Corsa again. The Corsa doesn't drone, but it is pretty much a straight pipe with noise cancellation chambers along the way so it is always loud behind the car...

I have never been pulled over with the stock mufflers (no resonator anymore, but it is still super quiet). It also doesn't make any extra top end at all. The cops hear you coming a mile away with anything good:p.

[Dynomite]

1991 with Offroad SW headers and SW exhaust, SD Plates, followed by CA Highway Patrol on motorcycle for one mile. He finally decided to just forget it and turned left as I turned right :D

[HAWAIIZR-1]

I have had at least 4 different exhaust systems that I can recall. Most of them are loud ;).

I have also ridden in a couple of flowmaster cat-back cars and a borla one with a resonator(just this morning and surprisingly not loud). The flowmaster ones rumbled and droned a bit and both cars had good top end pull.

The newest SW x-pipe does not contain the glasspack cheese grater insert...the mufflers sort of do, but the combined area of the twin outlets is far greater than that of one 3" pipe. The SW with X-pipe sounds just like the B&B and the quality is similar, but the registry does(did?) have that big discount on the SW stuff. The chambered muffs are plenty loud and drone like crazy. Pretty much the majority of C4 exhausts either drone and/or are very loud. I had to put the vacuum flappers on the straight thru part of my SW mufflers to get the 1/4 wave noise cancellation effect. This works really well, except it will still drone in 6th gear below 80 mph. The other gears worked well for me. I ran this system with headers- never with the stock manifolds.

I didn't like the Corsa- you could tell it wasn't quite making the top end the same as the big 3" pipe sets. I would much prefer to build a custom NPP valved turbo muffler on the stock 2.7" pipes before I would run a Corsa again. The Corsa doesn't drone, but it is pretty much a straight pipe with noise cancellation chambers along the way so it is always loud behind the car...

I have never been pulled over with the stock mufflers (no resonator anymore, but it is still super quiet). It also doesn't make any extra top end at all. The cops hear you coming a mile away with anything good:p.

Hey mike100,

Thanks for your reply and thoughts. It is always good to hear opinions from other members about the variety of options we have or had. I remember the group buy for SW and was not in the market at the time thinking I was going to modify the B&B system I already have on my 90. I do like the sounds of that system, but not the drone and I think I have 3rd gen so not too bad with resonator and know how restrictive that one is.

As I got older through the years, I know that I don't want drone/resonance that is bad. I think a little I can deal with, but I do plan to try to drive some distances with this 95 since it is more comfortable and I am in the upper 48 now. Thanks for the info about the chambered mufflers as the tech at SW told me that is the only system they sell and recommended for LT5 ZR-1s. He said because the drone/resonance is very bad with the other turbo S mufflers (aggressive) and apparently complaints from some customers.

I'm not sure yet if I will get headers and attempt to get pass the SMOG Nazis here in Cali. Even with A.I.R. tubes and I noticed you have them I guess it depends on where, when and who as to if you will get caught. I remember seeing yours is pretty stealthy from the top and can't tell so I might try to get a set converted (I still have my long tubes I removed from my 90 in Japan). So much work and hassle to get it done, but might venture into it next year. For now I just wanted to get a good exhaust system that was easy bolt on. I guess it does not exist depending on what I am really looking for. I know there are a lot of happy folks with the Corsas and it seems to be very high quality as is the price. I know I don't want to mess with OBX or Maximizer even though it is cheap and very similar to Corsas.

I guess I will take my time and not rush into this. I also thought about trying to modify the stock system with replacement of the resonator and mufflers, but would probably lead to resonance/drone too. According to Marc's info since I have a 95 no matter what I get it will only gain 5 HP so it is mostly sound I am after, but hard to find the right compromise. I am trying to imagine how cutouts would be, but can't imagine I would like to sound. Really messed up not being able to hear WARP10's (Bob's) at BG.

Thanks again for your thoughts and info. :handshak:

[mike100]

I had single outlet turbo mufflers on my last 95 LT1 car and it wasn't excessively loud. Previous to that the last owner had some 2.5" L98 Borla twin outlet mufflers put on and it was crazy- the single outlet thing is a must. I realize single outlet mufflers aren't very vette-like, but this was ok for 'ol purple-erkel during the year I owned it.
http://i29.photobucket.com/albums/c265/mschrameck/Cars/DSC03544.jpg~original (http://s29.photobucket.com/user/mschrameck/media/Cars/DSC03544.jpg.html)

That's why I suggested getting parts together for a custom NPP job on a more universal hi-perf muffler on the stock pipes. The NPP mufflers or flaps from a C6 are what will cost you. The rpm switch, junkyard solenoid, tubing, vacuum switch etc will be about $110. The project takes time- but it is fun to be able to have a selectable muffler. The other reason is I believe the stock pipe diameter and chosen pipe thickness is part of the acoustic engineering that went into it. I x-piped the resonator on my 1990 pipes and it barely got louder- I know if I cork up the right muffler and then have a flap on the second outlet, it ought to be able to stay similarly quiet. btw, my car is a 91, but I got Han's old 1990 stockers and Dominic's old Magnaflow x-pipe.

As far as the smog thing- yeah- I ran my headers while I could, but I drew the Star station inspection so I wasn't so sure I'd have a prayer at passing the extra thorough visual. The car is back to stock manifolds. I have to admit it is very tame to daily drive (but you don't really get used to losing the extra pop that headers, porting, and cat back gave you). Long term I'm looking into buying a cabin in an unenhanced zip code to get out of the bi-annual inspections, short term I'm thinking about doing NPP muffs as described above on my stock pipes since I have all the parts for the control side still hanging on my car.

[mike100]

One last thought on air injection tubes on headers: The Watson ones do not work- look at marc H's website articles on the matter... you have to keep the diameter right and the tube has to be far away from the header flange. The pressure is too great where the watsons go in and it will burn out your one-way check valves. I had to replace two or three of them when I put back my stock stuff. I will be taking those off next time around.

[HAWAIIZR-1]

I had single outlet turbo mufflers on my last 95 LT1 car and it wasn't excessively loud. Previous to that the last owner had some 2.5" L98 Borla twin outlet mufflers put on and it was crazy- the single outlet thing is a must. I realize single outlet mufflers aren't very vette-like, but this was ok for 'ol purple-erkel during the year I owned it.
http://i29.photobucket.com/albums/c265/mschrameck/Cars/DSC03544.jpg~original (http://s29.photobucket.com/user/mschrameck/media/Cars/DSC03544.jpg.html)

That's why I suggested getting parts together for a custom NPP job on a more universal hi-perf muffler on the stock pipes. The NPP mufflers or flaps from a C6 are what will cost you. The rpm switch, junkyard solenoid, tubing, vacuum switch etc will be about $110. The project takes time- but it is fun to be able to have a selectable muffler. The other reason is I believe the stock pipe diameter and chosen pipe thickness is part of the acoustic engineering that went into it. I x-piped the resonator on my 1990 pipes and it barely got louder- I know if I cork up the right muffler and then have a flap on the second outlet, it ought to be able to stay similarly quiet. btw, my car is a 91, but I got Han's old 1990 stockers and Dominic's old Magnaflow x-pipe.

As far as the smog thing- yeah- I ran my headers while I could, but I drew the Star station inspection so I wasn't so sure I'd have a prayer at passing the extra thorough visual. The car is back to stock manifolds. I have to admit it is very tame to daily drive (but you don't really get used to losing the extra pop that headers, porting, and cat back gave you). Long term I'm looking into buying a cabin in an unenhanced zip code to get out of the bi-annual inspections, short term I'm thinking about doing NPP muffs as described above on my stock pipes since I have all the parts for the control side still hanging on my car.

Hey, I really do appreciate all the info you are sharing and so much to consider. I'm glad I have folks to run this stuff by so I don't reinvent the wheel, especially with someone living in Cali that understands the pain to go through. I don't have much knowledge about SMOG too since only one truck (My 03 Lightning) and I don't count the wife's VW Golf since 2014 and just required by CA bringing the car in state.

I was thinking about the mufflers and what you mention about single tip. I already have a new set of Dynomax with single in/out 3" I was going to do some experimenting with my 90 B&B some years ago. I would have to probably get new 2.75 to match pipe if so or reduce the inlet and see how that works. I did find a 2.75 x pipe but have not confirmed the center to center and length to see how much work is involved or just go the Magnaflow (I almost bought one from Gunny a few years ago). I have to do more research about the resonator on the 95 to see how restrictive and worth the gain or resonance to eliminate with x pipe. The cool thing about the single outlet idea is I found a tip that looks just like stock on 95 with the wide single opening, but only 2 1/2" inlet. Then there are others that branch off into two tips from a single. Not sure if that is the route to go or like you said and build a custom NPP mufflers to stock pipes.

I'm on the fence to hack up the 95 exhaust and was looking to initially just remove and keep (but for what?). I always keep stock stuff that I will probably never use and all of it is just getting in my way. I have all the bolt on stuff from my 90Z, Lightning, and Harley and need to just get rid of the stuff. No more room. I have this thinking that the next owner will/may want all the stock stuff. WTF?

Thanks again for your thoughts and info. I wish you were a lot closer. Are you thinking about attending the ZR-1 Gathering in Vegas during Oct if that pans out?

:cheers:

[HAWAIIZR-1]

One last thought on air injection tubes on headers: The Watson ones do not work- look at marc H's website articles on the matter... you have to keep the diameter right and the tube has to be far away from the header flange. The pressure is too great where the watsons go in and it will burn out your one-way check valves. I had to replace two or three of them when I put back my stock stuff. I will be taking those off next time around.

Thanks for the info. I was going to send my current set or buy a set of OBX to have modded by Marc if so. I think Marc's would be modded like factory setup. Just trying to figure out the cats if so and did see that you found the Z06 or ZR1 cats to work and similar to size of ours. I even had a thought to have the stock manifolds extrude honed or ported, but it does not seem worth the effort if there is any gain compared to the cost. I do have an extra set of 93-95 manifolds to play with.

[HAWAIIZR-1]

I have to finish detailing this 95 later today for next week's car show so I'll get under the car and check out this exhaust system to see what other thoughts I have. I do remember seeing how it chokes up the pipe going into the mufflers and I remember so other choke point mentioned with the resonators?

[mike100]

From what I have heard that only the 1996 LT4 cars had a good resonator that didn't crimp down to a small diameter.

Interestingly there was also one year on Z51 L98 cars that had functional 2-outlet mufflers.

[HAWAIIZR-1]

From what I have heard that only the 1996 LT4 cars had a good resonator that didn't crimp down to a small diameter.

Interestingly there was also one year on Z51 L98 cars that had functional 2-outlet mufflers.

I read similar about those LT4 resonators and I wonder why only one year and only that engine chosen for use? If available, I imagine the cost is not worth the HP if any.

That is also interesting about the Z51 L98 too.

I can't seem to find a 2.75 X pipe and the one found earlier is 2.75 to 3.00 inch.

[Gunny]

I have SW headers, no cats, and the LT-4 exhaust on my 90. As far as I can tell the LT-4 resonator has very little restriction (perhaps the least of any C4 stock exhaust) plus it has an H balance tube behind the resonator. I'm very pleased with my setup. I could (should) live with the existing setup but I'm very curious about adding cutouts (ala WarpTen) and will probably do so in the near future. I've also thought about adding hi flo cats but may leave it as-is for now.

FWIW, I've had Borla 2.5 (stock manifold), Borla 2.75 (challenger system, headers, hi flo cats), Corsas (headers, no cats), stock 95 (headers, no cats), and finally my current setup. Spent too many $$$ from point A to point B but it was an interesting (even eye-opening ride). Main thing I learned is that exhaust is a highly personal, very subjective decision and what works for some will not work for others.

I think the improvements/developments made using the flapper system has been a great step in the right direction and opens up a lot of possibilities that we may yet not have seen.

I'll be curious to see/hear what you work out Craig. Give me a call sometime.

[mike100]

I read similar about those LT4 resonators and I wonder why only one year and only that engine chosen for use?...

I would imagine because they couldn't justify making another change to the LT5 system emissions-wise and paying for more retesting (for the 448 cars a year). The LT4 was a re-cert for OBD-2 so they probably were looking for a few more hp on the LT4 without adding more cam or ign timing so I bet the resonator was an easy area for improvement.

[HAWAIIZR-1]

I have SW headers, no cats, and the LT-4 exhaust on my 90. As far as I can tell the LT-4 resonator has very little restriction (perhaps the least of any C4 stock exhaust) plus it has an H balance tube behind the resonator. I'm very pleased with my setup. I could (should) live with the existing setup but I'm very curious about adding cutouts (ala WarpTen) and will probably do so in the near future. I've also thought about adding hi flo cats but may leave it as-is for now.

FWIW, I've had Borla 2.5 (stock manifold), Borla 2.75 (challenger system, headers, hi flo cats), Corsas (headers, no cats), stock 95 (headers, no cats), and finally my current setup. Spent too many $$$ from point A to point B but it was an interesting (even eye-opening ride). Main thing I learned is that exhaust is a highly personal, very subjective decision and what works for some will not work for others.

I think the improvements/developments made using the flapper system has been a great step in the right direction and opens up a lot of possibilities that we may yet not have seen.

I'll be curious to see/hear what you work out Craig. Give me a call sometime.

Hey George,

Thanks for your thoughts and info. Wow, you have had quite a few combinations of exhaust systems too. I am more confused than I ever was. I really wanted to just buy a bolt on system and call it a day. I really thought the SW system with chambered mufflers would fit the bill and maybe it still will.

I don't know if worth trying to do the LT4 resonator (maybe just replace with X pipe?), but I measured the outside (yes, outside) diameter of the pipe going into the 95 muffler and could not believe only 2.25". What the heck were they thinking? So the inside diameter is only a little over 2" depending on the gauge of steel used. Then the single outlet is only 2.25 in outside diameter too so it is really choked by the muffler too. I think it was Marc H that mentioned it on his study. I see why even the Corsa at 2.5 makes a difference by design.

I agree with you about subjective and very personal to find what each individual likes/wants, but it can get expensive quick by experimenting. Another thing is trying to find the right shop to do custom work can become very frustrating. I will give you a call so we can chew the fat about exhaust and other things. Thanks again and take care!! :handshak:

[HAWAIIZR-1]

I would imagine because they couldn't justify making another change to the LT5 system emissions-wise and paying for more retesting (for the 448 cars a year). The LT4 was a re-cert for OBD-2 so they probably were looking for a few more hp on the LT4 without adding more cam or ign timing so I bet the resonator was an easy area for improvement.

That makes sense. I did look at how the pipes get small going in and out of our resonator. I already had the car down so did not take measurements, but maybe same like the pipe going in and out of the mufflers at 2.25. So this 95 system is choked at the resonator and mufflers and still higher flow that the earlier years. No wonder it sounds like crap and muffled when recorded.

[Gunny]

.... (maybe just replace with X pipe?).....

I've also been interested in this mod to the LT4 system (or late LT5 system for that matter) ... I believe the X-Pipe "might" be an improvement. Talked with Tony D. at BG and he's experimenting with an H pipe and that sounds promising also. I would really like to hear/ride in a Z with the same setup I have except with the X-Pipe or H-Pipe replacing the resonator.

I think the next thing I want to try is cut-outs and perhaps that will be the last step. Each time I change something I swear it will be the last change but then the "bug" bites and I can't wait to try something else. One concern (fear?) is that I will arrive at an acceptable system (sound, performance, etc.) then take it one step too far. I've already done that a couple of times and it's frustrating ... but I suppose the "experimentation" journey can be fun at times ...:rolleyes:

[XfireZ51]

Like many on this forum, I did my bit when it comes to experimenting w various exhaust systems. Over time, I've "evolved". The exhaust system changed as the power levels changed (increased). So here's a summary of how things were modified.

1. stock motor, stock exhaust
2. Stock motor, B+B 3rd Gen cat back. ~ 340rwhp.
3. Stock motor, Watson 1 7/8"headers, B+B 3G. Drone
4. Ported Top End, headers, B+B 3G. Drone 387rwhp.
5. Ported Top End, headers, MagnaFlow cat back. Sweet exhaust note, ~400rwhp.
6. Ported heads, Intake cams, headers, Xpipe, MF muffs. Drone. ~420rwhp
7. Ported heads, I/E cams, headers, Xpipe, MF muffs. Drone ~440rwhp
8. Ported heads, I/E cams, headers, Xpipe, DynoMax, NPP tips. ~454rwhp.

HP numbers are all SAE corrected.

With tuning and using the NPP on/off, drone is pretty much eliminated. In fact, cruise is nice even w both tips open. With two tips open, the exhaust takes on a basso profondo note. The difference between open/closed tips is very noticeable at idle from inside the cabin.
I would also recommend installing fiberglass insulation or some type of sound deadner in the spare tire carrier.
THAT has really made the exhaust note very tolerable by dampening any vibration coming from the floor of the hatch area.
If you have a stock motor, I like the MF cat back. Did not find that resonator restriction really made a difference. It appeared fine supporting up to 400rwhp.
My one complaint is the hanger setup for these mufflers. Plainly, they suck and need to be modified. But the 3" SS pipe that came w the cat back is still part of my exhaust.
As before, I will emphasize the importance of tuning, and I mean part throttle/cruise, in taming the drone. Drone happens when opening the throttle where vacuum drops (ie higher MAP) and exhaust gets blubbery. So getting the AE ( pump shot) right and leaning out the mixture in that part of the fuel table goes a long way to reducing/eliminating the drone.
:cheers:

[HAWAIIZR-1]

I've also been interested in this mod to the LT4 system (or late LT5 system for that matter) ... I believe the X-Pipe "might" be an improvement. Talked with Tony D. at BG and he's experimenting with an H pipe and that sounds promising also. I would really like to hear/ride in a Z with the same setup I have except with the X-Pipe or H-Pipe replacing the resonator.

I think the next thing I want to try is cut-outs and perhaps that will be the last step. Each time I change something I swear it will be the last change but then the "bug" bites and I can't wait to try something else. One concern (fear?) is that I will arrive at an acceptable system (sound, performance, etc.) then take it one step too far. I've already done that a couple of times and it's frustrating ... but I suppose the "experimentation" journey can be fun at times ...:rolleyes:

Thanks for your thoughts George. I was trying to do some research on the LT4 resonator and an X pipe that would work to replace the LT5 resonator. My fear is that here comes the drone and not sure what exactly makes or breaks my level of tolerance. On one hand thinking to just leave it alone or just go with Corsa and deal with raspy. The other is to just put cut outs, but not sure what that sounds like and still have the choke point of resonator.

I received this back from SW rep about their system with the chambered mufflers:

XXXXXXXXXXXXXXXXXXXXXXXXXX


From: Joe Nagle [mailto:joe@stainlessworks.net]
Sent: Monday, June 15, 2015 5:13 AM
To: Craig
Subject: Re: ZR1 Exhaust

Hey Craig,

The design of the mufflers is one single 3" ID inlet with multiple perforated tubes that lead to the dual 2.5" outlets. Surrounding those tubes is 304 stainless steel wool packing that will never break down and blow out. This is our quieter setup for an exhaust. Drone is such a subjective term but I think you should be alright with this setup. Let me know if you have any further questions.

Joe

XXXXXXXXXXXXXXXXXXXXXXXX

Worst case scenario is try it and if I can't take it in regards to drone/resonance do the NPP Z06 valves to their mufflers. I really was trying to stay away from custom work as I don't have time to deal with that for another year.

Take care,
Craig

[HAWAIIZR-1]

Like many on this forum, I did my bit when it comes to experimenting w various exhaust systems. Over time, I've "evolved". The exhaust system changed as the power levels changed (increased). So here's a summary of how things were modified.

1. stock motor, stock exhaust
2. Stock motor, B+B 3rd Gen cat back. ~ 340rwhp.
3. Stock motor, Watson 1 7/8"headers, B+B 3G. Drone
4. Ported Top End, headers, B+B 3G. Drone 387rwhp.
5. Ported Top End, headers, MagnaFlow cat back. Sweet exhaust note, ~400rwhp.
6. Ported heads, Intake cams, headers, Xpipe, MF muffs. Drone. ~420rwhp
7. Ported heads, I/E cams, headers, Xpipe, MF muffs. Drone ~440rwhp
8. Ported heads, I/E cams, headers, Xpipe, DynoMax, NPP tips. ~454rwhp.

HP numbers are all SAE corrected.

With tuning and using the NPP on/off, drone is pretty much eliminated. In fact, cruise is nice even w both tips open. With two tips open, the exhaust takes on a basso profondo note. The difference between open/closed tips is very noticeable at idle from inside the cabin.
I would also recommend installing fiberglass insulation or some type of sound deadner in the spare tire carrier.
THAT has really made the exhaust note very tolerable by dampening any vibration coming from the floor of the hatch area.
If you have a stock motor, I like the MF cat back. Did not find that resonator restriction really made a difference. It appeared fine supporting up to 400rwhp.
My one complaint is the hanger setup for these mufflers. Plainly, they suck and need to be modified. But the 3" SS pipe that came w the cat back is still part of my exhaust.
As before, I will emphasize the importance of tuning, and I mean part throttle/cruise, in taming the drone. Drone happens when opening the throttle where vacuum drops (ie higher MAP) and exhaust gets blubbery. So getting the AE ( pump shot) right and leaning out the mixture in that part of the fuel table goes a long way to reducing/eliminating the drone.
:cheers:

Hey Dom,

Thanks for the detailed rundown that will help all considering any mods in general as well as the effect on components. It almost seems like X pipe equals drone....ha, ha and no surprise. Maybe those guys from Corsa are pretty smart after all with their H pipe built in and using a pretty free flowing resonator to still get HP without drone. I suppose they put a lot of research into it. I still have to hear that in person to know if I like it or not. The other thing is not knowing the future of my build. I am thinking I won't be pulling heads or putting cams in this car after going through that on my 90 and living here in Cali. I really have to get into this "tuning" stuff one day and have half of the things needed. I have stay at Holiday Inn, but don't feel comfortable any time soon to get into tuning 101 and beyond just yet.

Thanks for all the tips about insulation and will try to do as you suggest when the time come never thinking about the spare tire carrier. I wonder how a product like dynamat or something would work under the carpet on the inside too in the hatch area? Gotta run to work, but appreciate the info and tips. :cheers:

[HAWAIIZR-1]

Thanks for all the replies and greatly appreciated. I decided to give up on the SW chambered mufflers and not what I am looking for after all. I was hoping more than one person on here had experience with them. I'm going to look into unchartered territory with my quest for the perfect exhaust (for me and this car anyway). Marc Haibeck's study and information about exhaust system sure does explain a lot and made me rethink everything about what direction I want to head in. He is truly awesome for sharing his expertise with so much of what he knows so we don't reinvent the wheel.

[XfireZ51]

Craig,

It's not that Xpipe = Drone, it's that lack of resonator = drone. GM eliminated the resonator due to weight and restriction on the C6 Z06. Instead they used an Hpipe and the NPP valves to tame the drone.

[HAWAIIZR-1]

Craig,

It's not that Xpipe = Drone, it's that lack of resonator = drone. GM eliminated the resonator due to weight and restriction on the C6 Z06. Instead they used an Hpipe and the NPP valves to tame the drone.

Hey Dom,

Got that and understand how important those resonators are with preventing drone. Not that the one on my B&B helps much....my gen III system drones like hell too. I understand there is a lot of science behind all this frequency stuff and spent some countless hours trying to read about it, especially on C4s. So many dynamics change things in the exhaust system. Mike100 spent countless hours offline sharing what he learned over the years with trial and error as many others have done too. He also confirmed too the NPP is the way to go and I really see why GM went that route. I had high hopes for the SW chambered system since they listed in a few places that there was no drone, but it seems otherwise. I guess the only true off the shelf system without drone if you like the tone is the Corsas. :handshak:

Craig

[XfireZ51]

Porsche and BMW both use NPP valves.

[HAWAIIZR-1]

Porsche and BMW both use NPP valves.

German Engineering at its best and glad to hear GM jumped on the band wagon.

[HAWAIIZR-1]

Like many on this forum, I did my bit when it comes to experimenting w various exhaust systems. Over time, I've "evolved". The exhaust system changed as the power levels changed (increased). So here's a summary of how things were modified.

1. stock motor, stock exhaust
2. Stock motor, B+B 3rd Gen cat back. ~ 340rwhp.
3. Stock motor, Watson 1 7/8"headers, B+B 3G. Drone
4. Ported Top End, headers, B+B 3G. Drone 387rwhp.
5. Ported Top End, headers, MagnaFlow cat back. Sweet exhaust note, ~400rwhp.
6. Ported heads, Intake cams, headers, Xpipe, MF muffs. Drone. ~420rwhp
7. Ported heads, I/E cams, headers, Xpipe, MF muffs. Drone ~440rwhp
8. Ported heads, I/E cams, headers, Xpipe, DynoMax, NPP tips. ~454rwhp.

HP numbers are all SAE corrected.

With tuning and using the NPP on/off, drone is pretty much eliminated. In fact, cruise is nice even w both tips open. With two tips open, the exhaust takes on a basso profondo note. The difference between open/closed tips is very noticeable at idle from inside the cabin.
I would also recommend installing fiberglass insulation or some type of sound deadner in the spare tire carrier.
THAT has really made the exhaust note very tolerable by dampening any vibration coming from the floor of the hatch area.
If you have a stock motor, I like the MF cat back. Did not find that resonator restriction really made a difference. It appeared fine supporting up to 400rwhp.
My one complaint is the hanger setup for these mufflers. Plainly, they suck and need to be modified. But the 3" SS pipe that came w the cat back is still part of my exhaust.
As before, I will emphasize the importance of tuning, and I mean part throttle/cruise, in taming the drone. Drone happens when opening the throttle where vacuum drops (ie higher MAP) and exhaust gets blubbery. So getting the AE ( pump shot) right and leaning out the mixture in that part of the fuel table goes a long way to reducing/eliminating the drone.
:cheers:

Dom,

I was thinking to myself and doing the math. You have more hours than I can imagine perfecting your car and tuning it over the years. I hope to get to the point in my life that I can spend more time to learn and understand these cars. I can't remember the TV program I saw many years ago, but this guy had a C4 (back then I was not into them) and guessing it was an LT1 car or maybe it was a ZR-1. He made some crazy horsepower doing just fine tuning to many different components of the car. I can imagine that only a small percentage of our cars are really tuned to squeeze the max out of the car. In the old school days even though there weren't computers, if you matched the right components together from the entire set up and tuned it right it was like the stars aligned and you would hit the G spot to make the car scream. Well, I'm way off topic now and I guess okay since I am the OP.

Anyway, I guess my small way to say thanks for your invaluable input and insight as always.

Craig