NPP Exhaust
 

I'm sure this topic has come up before but I am trying to figure out if my Vette has the NPP exhaust or not. I read somewhere that the NPP exhaust would have 4" tips (non NPP would have 3" tips). Mine are 3" tips and I cannot notice a difference in sound when I change the mode from Track to Sport, to Touring, etc, in the engine sound management. I guess if I don't have it, then why would there be an option to change it in the infotainment screen?

Also, I've also read that there is a fuse one can remove that would open the baffles/valves all the way so it'd always sound like NPP exhaust in the Track mode. Is this accurate and if so, would anyone advise removing a fuse?

Welcome to the forum.

On the C6 you could see the vacuum operated valves just ahead of the tips. Not sure how the C7 system worked.

On most GM cars there is a sticker inside the glove box that lists all the options that the vehicle was built with.

Unfortunately, mine didn't have the sticker in the glove box (I didn't buy it brand new; as I'm the second owner).

In that case I believe you can order a window sticker from the National Corvette Museum. That would give you a definite answer on your question.

Thank you 73shark! I think I'll do that. I actually found a little flyer in the glove box, giving me a free one year subscription to the NCM. Needless to say, already signed up!

The tips appear to be the same, however, if your car isn't substantially louder at idle in Track or Sport mode then you probably don't have NPP. You can also inspect the exhaust tips closer and see if they have lines for the actuator that opens the flaps for NPP. For 2014 models you need to pull fuse 41, this changed to location 42 (still same physical location) in years 2015 and further. This will cause the NPP to remain open at all times, regardless of what mode you in. This also makes the V4 eco mode run like crap (beware).

If they haven't fixed the oiling problems created by AFM, probably should disable it. A lot of the GMT900s lunched engines because of AFM.

Someone correct me if I'm mistaken, but I was under the impression that just pulling the NPP fuse has ZERO impact on AFM, and I'm only stating that when the NPP is open the Eco mode exhaust sounded odd.

That being said, I don't plan to use Eco mode when driving the car, with the fuse out. If I plan to take a trip that I would use Eco, I will simply reinsert the fuse that is stored inside the box.It's a 90-second reversal to get a real exhaust note out of the car (at all times). You guys running around in "Sport" are missing some exhaust love due to sounds restrictions forcing NPP to close.

I believe you are correct. The only way I know to defeat the AFM is by using the Range Technology AFM disabler or through a custom tune.