C7 exhaust

[David123]

So after my recent c7 purchase I have spent literally a week watching exhaust videos and reading forum . If anyone can answer the following questions I would be grateful -

1) I am now reading that replacing my oem x pipe and secondary cats with an aftermarket replacement x pipe can cause a loss in power if the car isn’t re tuned ?
2) I have watched numerous videos on axle back after market exhausts …. Some just delete the whole npp valve system which is fine .. but what confused me is that some aftermarket exhausts delete the AFM (air fuel mixture sensors) that are situated before the muffler .. surely this upsets the running of the car ?

any recommendation re aftermarket exhausts without having to retune the car ? Thanks

 

[Chevrolet]

What are you looking for? More/different noise, more power or both? Guess you have been looking at videos of mainly Borla, Corsa. Flowmaster etc exhausts?

Did you see this one? I am guessing this will apply to UK spec cars too? I know several guys up in Notts with UK spec C7s, but they are all autos and none of them have gone for aftermarket exhausts or tried the below.

 

[teamzr1]

So after my recent c7 purchase I have spent literally a week watching exhaust videos and reading forum . If anyone can answer the following questions I would be grateful -

1) I am now reading that replacing my oem x pipe and secondary cats with an aftermarket replacement x pipe can cause a loss in power if the car isn’t re tuned ?
2) I have watched numerous videos on axle back after market exhausts …. Some just delete the whole npp valve system which is fine .. but what confused me is that some aftermarket exhausts delete the AFM (air fuel mixture sensors) that are situated before the muffler .. surely this upsets the running of the car ?

any recommendation re aftermarket exhausts without having to retune the car ? Thanks

As I mentioned in another post, doing a CAT back only changes the sound and no performance gains
Changing from a H pipe to X-pipe in mid-pipes only balances the sound left/right

People are known to spend $2,000 to $4,000 in thinking there is a performance gain to have a midlife crisis after all the costs and
zero gains

Next is the stock NPP valves

If the C7 has 8 speed auto tranny, there are another 2 NPP valves (4 total) closer to the engine and are needed for more back pressure when the AFM kicks in
AFM is what commands via the PCM going from 8 to four cylinders mode and back

If having the manual 7 speed tranny only has 2 NPP valves by mufflers and PCM commands the butterflies wide open when doing WOT

Yes, owners ask me when I tune the PCM to turn off AFM, but that is more for people want 8 cylinders all the time
Vendors who sell high cost CAT backs, some replace the stock NPPs with theirs and are not exact to stock ones
and can cause error codes to trip, and you have to solve that with tuning, so be sure the seller in writing says their NPPs will not trip DTCs

If installing a CAT back with no NPPs then either have to buy and install NPP simulators so DTCs do not trip or turn off those DTCs

In the end if all you want is exhaust sound change is replacing stock mufflers, fewer costs and less hassle