Add NPP to exhaust?
Thread Starter
Intermediate
Joined: Oct 2025
Posts: 42
Likes: 9
Add NPP to exhaust?
Are there any kits for this? My car came with a very loud track exhaust. It's great on the road but cold start from inside my garage makes the neighbors jump out of their skin. If I wanted to leave the house late at night there is no way I would start that car and would have to take my Suburban instead.
Burning Brakes
Joined: Jul 2021
Posts: 823
Likes: 471
From: Edgewater, FL
2024 C7 of the Year Finalist - Unmodified
First question. Did your car come from the factory with OEM NPP exhaust option? If yes is the wiring still there and intact?
If you have the OEM wiring there is a set of NPP muffles on the for sale forum, here is a link, https://www.corvetteforum.com/forums...hlight=exhaust, they are available in the central Florida area.
I am not sure if those ones have AFM valves or not if you car needs the AFM system.
If you car did not come from the factory with NPP option, then it is very difficult to fit them to your car and have them fully functionable. There are numerous posts on the forum about the modifications needed to convert a non NPP equipped car to accept a functioning NPP system.
Hope this helps.
If you have the OEM wiring there is a set of NPP muffles on the for sale forum, here is a link, https://www.corvetteforum.com/forums...hlight=exhaust, they are available in the central Florida area.
I am not sure if those ones have AFM valves or not if you car needs the AFM system.
If you car did not come from the factory with NPP option, then it is very difficult to fit them to your car and have them fully functionable. There are numerous posts on the forum about the modifications needed to convert a non NPP equipped car to accept a functioning NPP system.
Hope this helps.
Thread Starter
Intermediate
Joined: Oct 2025
Posts: 42
Likes: 9
First question. Did your car come from the factory with OEM NPP exhaust option? If yes is the wiring still there and intact?
If you have the OEM wiring there is a set of NPP muffles on the for sale forum, here is a link, https://www.corvetteforum.com/forums...hlight=exhaust, they are available in the central Florida area.
I am not sure if those ones have AFM valves or not if you car needs the AFM system.
If you car did not come from the factory with NPP option, then it is very difficult to fit them to your car and have them fully functionable. There are numerous posts on the forum about the modifications needed to convert a non NPP equipped car to accept a functioning NPP system.
Hope this helps.
If you have the OEM wiring there is a set of NPP muffles on the for sale forum, here is a link, https://www.corvetteforum.com/forums...hlight=exhaust, they are available in the central Florida area.
I am not sure if those ones have AFM valves or not if you car needs the AFM system.
If you car did not come from the factory with NPP option, then it is very difficult to fit them to your car and have them fully functionable. There are numerous posts on the forum about the modifications needed to convert a non NPP equipped car to accept a functioning NPP system.
Hope this helps.
Burning Brakes
Joined: Jul 2021
Posts: 823
Likes: 471
From: Edgewater, FL
2024 C7 of the Year Finalist - Unmodified
Maybe I miss understood the intent of your question, yes that is a factory exhaust with NPP valves, as far a retrofitting your AWE with NPP valves, I would not know. The best way to find out maybe would be to contact AWE to see if they offer a kit or know of someone that does offer a kit to add the NNP valves between the mufflers and the tips. My gut feeling is that will be a non starter
Burning Brakes
Joined: Mar 2022
Posts: 1,220
Likes: 733
From: Phoenix, Arizona
If the exhaust you have is that pic you sent, there is no way an NPP will quiet that down - it's straight piped. Maybe you could find someone local to trade for one with NPP that they don't think is loud enough for them? I've always wondered what that system you have sounds like in person, but I'd bet there are times you don't want to be so noticable too
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
I have a 2017 Grand Sport so I am assuming that it does since it's a 2lt and has all the options. That looks like a stock exhaust? I have an AWE track exhaust, can the valve system be put into this? Or are you referring to removing it from the stock exhaust system to add to mine?
All the NPP valves do is force the exhaust flow to follow a different path. When open, the flow is straight through the muffler like a straight pipe. When closed the flow is diverted into the muffler and the muffler does what it's supposed to....absorb sound and quiet things down.
Thread Starter
Intermediate
Joined: Oct 2025
Posts: 42
Likes: 9
If the exhaust you have is that pic you sent, there is no way an NPP will quiet that down - it's straight piped. Maybe you could find someone local to trade for one with NPP that they don't think is loud enough for them? I've always wondered what that system you have sounds like in person, but I'd bet there are times you don't want to be so noticable too
Thread Starter
Intermediate
Joined: Oct 2025
Posts: 42
Likes: 9
No it cannot. Even if you welded the NPP valves into the AWE system, you have no muffler body to divert the sound to, not to mention you'd be restricting exhaust flow by 90%+ in which case the engine likely won't run.
All the NPP valves do is force the exhaust flow to follow a different path. When open, the flow is straight through the muffler like a straight pipe. When closed the flow is diverted into the muffler and the muffler does what it's supposed to....absorb sound and quiet things down.
All the NPP valves do is force the exhaust flow to follow a different path. When open, the flow is straight through the muffler like a straight pipe. When closed the flow is diverted into the muffler and the muffler does what it's supposed to....absorb sound and quiet things down.
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Drifting
Joined: Dec 2019
Posts: 1,816
Likes: 616
From: Blacksburg Va
If the exhaust that is on there now was installed w/o modifying the rest of the system, you could buy a set of used NPP mufflers and install them. I got mine for about $550 but that was 5 years ago.