Cutouts - any performance issues?
 

I am about to install a set of exhaust cutouts on my 2011 vert ss (stock except for CAI), and am wondering if this will cause any performance or code related issues. I plan on installing just after the cats, and I don't have enough room back by the diff, with all the vert bracing. As it is I am replacing the trans tunnel bracing with a custom brace to make room up front as well.

Do these engines need back pressure from the exhaust to run properly? Will I be giving up low end torque?

Any thoughts are appreciated.

Well for one you will have flames so hopefully they are directed down and out, and may cause a CEL from the increase in exhaust flow compared to stock... Why not go headers and catback....? Back pressure is more a myth for making things :"run right". My car is a LS3 I get enough decel popping from the fuel cutoff anytime I go from gear to gear down , or let off throttle to worry if I had cutouts that I would have to have it altered to try to remove it in the tune and run richer so I would not be the backfire mobile.....shooting flames under my seat is not what I want.... Some people have done this maybe they will chime in. But if they went with stock exhaust.....

You won't be losing much torqe bottom end. I just watched that Hotrod muffler test posted on the forced induction section 2.5" vs 3" and they did a test just running the headers with nothing else and it made more power everywhere except a tiny bit below 2000rpm or something. Which you'll never see that rpm anyways when you're racing. I've took my stock hpipe off and ran it for a couple weeks with no check engine light so you should be fine with that as well. I wouldn't worry about the flames either. You're car has 4 cats stock anyways that you're leaving on plus the shielding in the tunnel.

I've had QTP's for 4 years installed right behind aftermarket headers with HF cats with stock exhaust without an issue. No flames. No CELs. Marginal power difference on the dyno. Open was about 5 hp less than closed. Go figure. Stock is faster and better in this case, but cutouts sound better.

Make sure you keep them clean and never operate them under pressure. I always open and close them under idle only.

Hope this helps.

Thanks for the feedback. The reason for doing cutouts is because dw doesn't want any additional exhaust noise over stock. She doesn't even like my bro's LS3 with a muffler delete. So, a cutout keeps her happy and gives the car a little character;)

I am going to take one more look at installing near the muffler but if not, it sounds like after the cats is ok as well. I will try to have them pointed down a little to keep heat off the floor.

I have QTP's installed and love them.

Sounds like you need a dual mode......with a forza threeway switch, but of course convertibles did not come with it... BTW your in Michigan you should ask her if she likes the sound of a hot rod and tell her to STFU cool is not a pink chicks car, grow a pair or turn your car in.... LOL Build it if you have it, if not its going to taste bad down the road and your displeasure for the car being dusted with doors on the side of the road well....that leads to guys buying things like mustangs that are factory trying to sound louder on purpose. What you have smog there? I would be at Livernois ..... like I said maybe you could dual mode, headers, hfc, cam and she would not divorce you but rather grab her crotch and make monkey noises like Tim the tool man .... As any good performance mod 1/4 way to 1/2 way just does that.... Somebody needs a trip to the track, go big of go home..........LOL My wife loves my Camaro...... And since when do we do everything to please our wives.... LOL Wait is this hers.............

Muffler delete is What some do, its also of course illegal: and on some sounds better than the stock trash cans out back, but thats why dual mode,... and it sounds better by far. Good Luck .

I had QTP cutouts installed on my modded camaro. (headers, cam, intake custom tune etc.) The car made less power with cutouts open. I saw this with my own eyes on the dyno. Made a run with and without them open.

but i still ran the cutouts because i loved the sound and made enough power than i didnt even care. like 10WHP loss.

I have them installed and LOVE them! Especially love the remote control feature. My car isn't stock though....so I can't comment on what they're like on a stock set-up.

It all depends on the placement of them.

I actually gained 9HP with the cutouts open on a SuperFlow Dyno. They are placed right after the first bend in the exhaust, which is right below my knees area. Some guys have had issues the closer you place them to the motor.

I didn't Install my cutouts for anything performance related. I've read some people have gained 5-10 hp a friend of mine actually gained like 8hp but apparently the person above me lost power. I have heard that cutouts can cause false knock but I just installed them for the sound they sound badass when you are cammed and WOT it's awesome

Agreed!

Agreed!

Agreed!

Thanks for the feedback. I am only doing this for more sound and character and just wanted to confirm that I wouldn't negatively impact oerformance, throw cels, etc. Sounds like it should be fine. Now if only I can find space underneath the vert!