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Yep, changing mufflers not a problem. With NPP you have a low exhaust restriction, aftermarket would be similar.
Changing to what folks say they have done using an X Pipe could be a question IMO. Probably not although what is called an aftermarket X Pipe is really a set of pipes that eliminates the secondary CATs! All C7's have an X-Pipes as Vettes have for a number of years.
Eliminating the main CATs or adding headers (that require a tune) is definitely an issue. In fact anything that requires a tune will void a warranty.
C7 OEM X Pipe with CATs, left; Bolra X Pipe (no CATs) center; Corsa Double X Pipe (no CATs) right
Xpipe will not cause warranty denial from what I am seeing. I agree with Jerry once you start need a tune that's where I would be reluctant to mod.
Removing the secondary CATs probably not an issue with GM since there are no oxygen senors providing exhaust chemistry feedback after them. Probably like a low restriction air filter or system, the existing air/fuel MAPS will handle any changes required.
However for those in CA, where inspection doesn't allow changes to any pollution equipment IF the inspector looks through the spaces in the metal exhaust pipe cover he'd see no secondary CATs and you'd flunk!
First Smog inspection in California for a new car is 6 years so who cares? After 6 years if you decide to keep the car and still live in California it might be an issue. They might not even notice and it could actually pass Smog. If they do notice and you fail just have it removed. Most places will do a retest for free and there are no fines for failing. Really isn't a big deal. BTW some Counties in California don't even require a smog.
Originally Posted by JerryU
Removing the secondary CATs probably not an issue with GM since there are no oxygen senors providing exhaust chemistry feedback after them. Probably like a low restriction air filter or system, the existing air/fuel MAPS will handle any changes required.
However for those in CA, where inspection doesn't allow changes to any pollution equipment IF the inspector looks through the spaces in the metal exhaust pipe cover he'd see no secondary CATs and you'd flunk!
Last edited by wonka12_98; 07-09-2017 at 05:49 PM.
A Corsa or Borla exhaust is fine-it will not void your warranty. The thing that will cancel out your warranty is if your car needs a tune. That could be a result of aftermarket headers.
Assuming that you have a GS as shown in your avatar, just swapping out your mufflers isn't going to gain you anything over your stock NPP mufflers when they are set on Track mode.
Aftermarket X-pipe that ditches the secondary cats would be the bigger bang for the $$$.
An often overlooked option is what I'm running which is Kooks 1 7/8" long tube headers + Kooks x-pipe w/Green cats + stock NPP mufflers. I still have the flexibility to run it quiet when needed or loud when I want it. The beauty of the Green cats is that I'm still running the stock tune and no check engine light (also running stock air filter and air intake system). Once the my car is out of warranty, I will tune it to wring out a little more power, but I only wanted the headers for the sound improvement and mission was accomplished.
07-09-2017, 10:22 AM
Removing the secondary CATs probably not an issue with GM since there are no oxygen senors providing exhaust chemistry feedback after them. Probably like a low restriction air filter or system, the existing air/fuel MAPS will handle any changes required.
