Finally getting my ZR-1 back from Corey's!!!

[EvanZR1]

On the flight down right now to pick up the Z from Corey Henderson's. Following is a brief list of all the work that was done:
OBX Long Tube headers installed
Fuel Injectors installed (from Fuel Injector Connection)
4.10 speedo gears installed
C4 beam plates
Removed secondary throttle blades
new plugs
Updated top end port work
Dyno tune

Final numbers were 360RWHP, which while not earth shattering is way better than the 300RWHP that I was getting. Corey said it didn't look like the secondaries had been working in quite a while. He also said the he would guess that I could probably gain another 20HP with a better flowing exhaust (currently have a Borla) and maybe a 160 thermostat. I was also thinking that I should probably MAT sensor relocation too. He said he was about 2.5 degrees short of where he normally can set the timing to without knock. I didn't have time to really talk with him in depth as he was finishing up and getting ready to go to BG. For any of you interested in OBX headers, make sure you ask him his opinion if you are there. If not, I will request a full email opinion on them and post it on here later.

Can't wait to get there and drive the car. Should definitely be a lot of fun now!

[Kevin]

please request an email from him as i won't be able to make it to bg this year

[EvanZR1]

Already requested. His initial comment was that they took a little "tweaking" to fit right. Also, he's not sure how much of the power I'm leaving on the table is the headers and how much is the Borla exhaust. My guess is the Borla as it really constricts before going into the resonator.

[PhillipsLT5]

Corsa time

[Kevin]

Originally Posted by PhillipsLT5

Corsa time

i think you meant b&b

[tf95ZR1]

It's the Borla resonator that is restricting.
Switch it out for a B & B X-pipe.
You will gain the HP.
How do I know.........

[PhillipsLT5]

I think you may get drone from B&B
Thats why I like the Corsa, no drone

[EvanZR1]

I think I'm going to try replacing the resonator with an x-pipe first and see what that does. It's a whole lot cheaper than a completely new exhaust.

[xlr8nflorida]

Originally Posted by EvanZR1

I think I'm going to try replacing the resonator with an x-pipe first and see what that does. It's a whole lot cheaper than a completely new exhaust.

I have a good amount of HP. I don't think you are leaving anywhere near 20 hp on the table at the 360hp level. Yes, the Borla restricts at the resonator. However, it sounds good if you like fairly quiet and no resonance. I hate resonance.

The most you are leaving on the table is 5-10 hp on account of the resonator. You can modify your existing reasonator or get an LT-4 resonator. The X pipe will make resonance.

Headers definetly give you 20hp and with a good exhaust you are golden.

To me anyway, unless its 20HP increase or more, the seat of the pants dyno is not affected.

I understand maximizing HP especially cheap hp. Just keep in mind there are trade offs.

I think you can gain 20hp by switching from Borla to B&B which is a bigger less restrictive system and also much louder with more rumble.

The exhaust claims I think are overstated. When the Borla came out in 1990, I have an ad that came from a reputable shop in Florida, I think it was in corvette fever, it says 40 HP increase from exhaust over stock - I'm sorry no way do I believe it. I think half the time you have to cut the claims in half in most people's applications.

Good luck do your research, I have thought about the X pipe as well and asked about it in the past. Most concur X pipe equals resonance. I am happy at my HP level so I have decided I don't need the extra 5-10hp.

I have thought about modifying my resonator or switching it out but not sure how that would turn out in the end. Marc Haibeck can give you more information on it, I think he even has an article about it.

I am not a big fan of the borla tips and how they hang. I have found a few nice examples of B&B tips and have thought about changing them out. I just need to find a good welder and an exhaust shop I can trust.

The Borla gets alot of bad press but I like it. It's more of a "sleeper exhaust" and does not have drone. I have heard all the others. The one that appeals to me is the B&B but sometimes I think it is too redneck for my tastes. It sounds nasty and like a racecar but as I get older, I like a more understated exhaust. Maybe its all the imports with fart can exhausts that turned me off to the loud exhausts.

Good Luck

[EvanZR1]

Hmm, might have to try an LT4 resonator. I really don't like drone. My 92 LT1 had no mufflers and an x-pipe, and it was a little too much.