Driver impressions from those who did some porting please

[WARP TEN]

Originally Posted by Gunny

For the "sleeper" idea, consider this ...
4:10, porting, headers, and late C4 stock exhaust with electric cutouts. Try to locate a 95 stock ZR-1 exhaust or a 96 LT4 exhaust. Install a pair of QTP electric cutouts just ahead of the muffler inlet. The cutouts are controlled by a switch located to your convenience. Totally open it's very close to running open headers - totally closed it's almost stock sounding (headers add a nice touch) - partially opened to taste, you can pick the sound that you like. Drone is only present when you open more than half-way.

I've had the stock system on my 90, 2.5" Borlas, 2.75 Borla Challengers, Corsas, stock 95 exhaust, and finally the stock 96 LT4 w/cut outs, SW headers, and porting by Marc.

Highly recommended: listen to & ride or drive as many Z's with different setups before you start modding your exhaust ... it will save time & money in the long run.

Bill, George is right--If you like a sleeper look but the ability to add power and be very loud when you want it, go for headers (with or without cats), a stock '95 system with cutouts. I used Corsas for years and they had a great sound and were the best to minimize drone, but in my old age I got a little tired of a loud exhaust all the time. This allows you to be almost as quite as stock (which still sounds pretty good) when you want it, but loud and open for power when you want it also. Allows you to preserve the spare tire carrier which I wanted. Based on Tony Davila's idea, I had Marc H. install mine right in front of the stock mufflers with a rocker switch hidden under the carpet on the passenger side of the console within easy reach. Relatively quite when closed, and basically straight pipes when open. I usually ran about one third open for some solid rumble. Wide open for racing and when I wanted to scare pets and small children. Here are a couple of pics--I have more pics if you decide to go this route. There is a video on my YouTube page of me running at NCM Motorsports park with them open if you want to hear what they sounded like. Here is a link: https://www.youtube.com/watch?v=DBwKZrENBS0&t=615s --Bob

[-=Jeff=-]

Bob,

what do you mean by 1/3 open? 1/3 of of the time? or was it an adjustable cutout?

[WARP TEN]

Originally Posted by -=Jeff=-

Bob,

what do you mean by 1/3 open? 1/3 of of the time? or was it an adjustable cutout?

Hi Jeff--
Yes, the cutouts were adjustable via the switch and electric motors on the cutouts. You can see the bottoms of the motor cans above the cutouts in the second picture in my post. My wife wanted the car quite when I was within our subdivision so I closed them when coming home or leaving. But then opened them up a bit if I felt like a little bit of loud exhaust. Usually about 1/3 open (I am guessing here) provided the right amount of sound for me. --Bob

[-=Jeff=-]

Do you know what brand the cutouts were?

Thanks

[WARP TEN]

Originally Posted by -=Jeff=-

Do you know what brand the cutouts were?

Thanks

Yes they were Quick time Performance or QTP cutouts which I think we got from Summit. I also added the little extension downturn which I painted flat black. Wanted to direct exhaust somewhat way from the tires, even though it is not too hot by the time it gets back there. The switch they send with them is just a big toggle switch which I didn't like so the rocker switch is my invention and worked well. There is a discussion of the switch installation and more pictures on a different thread here. Here is a link on the switch but there are lots of threads on cutouts. http://www.zr1.net/forum/showthread....hlight=cutouts --Bob

[Gunny]

After reading Tony's writeup about his cutouts and seeing Bob's installation I had a pair of QTP cutouts installed just before the muffler inlets. A good exhaust tech can make the QTP fit very nicely with a short turndown pipe (painted black) that is very difficult to see unless you lean down and are looking for it. Marc placed the toggle switch in an area aft of the emergency brake lever ... it's essentially hidden but easily accessible with the left hand. The toggle switch is a DPDT self centering switch ... hold it up to open the cutouts/down to close. It's very easy to open/close the cutouts to any position between fully open or fully closed.

I'm running headers/no cats with the stock 96 LT4 exhaust ... the resonator is said to be the most free flowing of all the stock C4 exhausts plus there is a balance tube (H-pipe) behind the resonator. My system totally closed sounds good (at least to me) probably because of the headers/no cats and only gets better as you open the exhaust up. I'm guessing that my best sound with no drone is somewhere between 1/3 & 1/2 open ... beyond that, the dreaded 6th gear drone becomes a factor; but when I'm running totally open, I rarely use 5th or 6th.

Like Bob, I tried other systems and even liked them, until the sound and/or drone became too much. For me this provides the best solution. btw, this setup can provide huge grins, especially in enclosed parking garages

[-=Jeff=-]

Gunny, how is the odor from having no cats? I found it a bit much on my Borla challenge system and I have cats with Corsa currently

[Gunny]

no odor detectable above 70 mph

in retrospect I probably should have used some high flow cats. I don't have a good sense of smell so it doesn't bother me much; but when I'm leading a caravan, those behind me with sensitive noses have complained. I imagine I will add the cats back to solve that issue ...shouldn't hurt the sound any nor have too much negative impact on HP/torque

[-=Jeff=-]

Thanks Gunny, I just snagged a LT4 system locally. Now to get it installed with my C6Z06 cats


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[Gunny]

Let me know how that works out. I think the C6Z cats are a good idea ... wouldn't mind scoring a pair for my setup. Take pics of the install.