NPP Question
Thread Starter
Melting Slicks
Joined: Mar 2003
Posts: 2,928
Likes: 55
From: Port Saint Lucie, Florida
NPP Question
Hi
I have a 2007 vert and would like to have a more aggressive sound! Right now l am spending a lot of $ on my house so an exhaust system is out of the question.
I have heard good things about the NPP system but no clue on what l would need to accomplish this. Plus the approx cost and approx cost to revert it back to stock the right way and not a patch job.
Thanks
Alan
I have a 2007 vert and would like to have a more aggressive sound! Right now l am spending a lot of $ on my house so an exhaust system is out of the question.
I have heard good things about the NPP system but no clue on what l would need to accomplish this. Plus the approx cost and approx cost to revert it back to stock the right way and not a patch job.
Thanks
Alan
Team Owner
Joined: Sep 2005
Posts: 20,352
Likes: 568
From: Ventura County, Calif
2 NPP mufflers.....anywhere from about $600 - $1000 used.
1 "NPP in a Box" kit (there are at least 2 kinds) to supply vacuum and control...$150 - $200.
Someone to install....cost varies widely....I would guess $150 - $250 (unless you can do it).
The caveat is NPP model years. If you can find a set from an '08, they will bolt right in.
But GM changed the passenger side over axle pipe slightly in '09 so anything from '09 up will not bolt straight in. A good exhaust shop can make it work by bending your car's x-pipe or making an adapter of some kind, probably not what you would want.
So if you find an '09 or newer NPP set, the best thing to do would be to also buy the accompanying '09+ x-pipe or buy a new one from GM. I don't know what they cost from GM.
1 "NPP in a Box" kit (there are at least 2 kinds) to supply vacuum and control...$150 - $200.
Someone to install....cost varies widely....I would guess $150 - $250 (unless you can do it).
The caveat is NPP model years. If you can find a set from an '08, they will bolt right in.
But GM changed the passenger side over axle pipe slightly in '09 so anything from '09 up will not bolt straight in. A good exhaust shop can make it work by bending your car's x-pipe or making an adapter of some kind, probably not what you would want.
So if you find an '09 or newer NPP set, the best thing to do would be to also buy the accompanying '09+ x-pipe or buy a new one from GM. I don't know what they cost from GM.
Le Mans Master
Joined: May 2000
Posts: 7,033
Likes: 12
For $850 I have a FULL Z06 exhaust on my car. Manifolds, cat pipes, H pipe, bi mode mufflers, 3 way solenoid, remote switch, check valve, and vacuum lines, which make the bi mode fully operational from my homelink visor. Not only does it sound a ton better than the stock exhaust (I have modded mufflers) it is probably worth 25-30rwhp over stock being the full Z06 exhaust.
Last edited by hippy; Oct 10, 2015 at 11:48 AM.
Race Director
Joined: May 2004
Posts: 16,667
Likes: 1,209
From: Raleigh, NC
St. Jude Donor '15
I've got about $700 in mine.
That is Z06 headers, Z06 cats, H pipe and modded Z06 NPP mufflers. Basically, a full 3" Z06 exhaust system from engine to tips.. I just ran the vacuum controlled valves on the mufflers directly to a vacuum source. They open about the right time.. you don't have control over it this way, but it is simple and has worked really well for me.
Several vendors have piles of these laying around from doing header/exhaust installs
Base 2007's have a 2.5" system, the Z06 stuff is 3".. so that's why I did it all. I think there's a 2.5" version of the NPP version but I can't remember what it's used on
That is Z06 headers, Z06 cats, H pipe and modded Z06 NPP mufflers. Basically, a full 3" Z06 exhaust system from engine to tips.. I just ran the vacuum controlled valves on the mufflers directly to a vacuum source. They open about the right time.. you don't have control over it this way, but it is simple and has worked really well for me.
Several vendors have piles of these laying around from doing header/exhaust installs
Base 2007's have a 2.5" system, the Z06 stuff is 3".. so that's why I did it all. I think there's a 2.5" version of the NPP version but I can't remember what it's used on
Last edited by schpenxel; Oct 10, 2015 at 01:26 PM.
Pro
Joined: Jun 2015
Posts: 729
Likes: 97
From: Lancaster NY
I just did an NPP retrofit on my '06. I found a pair of low mileage NPP mufflers off of an '08 (direct fit) on Craigslist for $275. I paid $150 to have the stockers removed and these installed. I then purchased the "NPP in a Box" kit which gives you the vacuum lines, tap, and wireless controller for $180 from a vendor here on the forums. It took me about 2 hours to install the NPP in a Box. Total cost was $605 and well worth it!
Le Mans Master
Joined: Mar 2001
Posts: 8,435
Likes: 3,922
From: Omaha
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
No, not really. Maybe 20HP going from a base exhaust to full Z06 exhaust. I got 14RWHP on my 2013 GS (which had NPP) when I did it, and that included eliminating the second set of cats that they added in 2012. It does sound good though, and even better if you gut the LS7 cats.
Le Mans Master
Joined: May 2000
Posts: 7,033
Likes: 12
No, not really. Maybe 20HP going from a base exhaust to full Z06 exhaust. I got 14RWHP on my 2013 GS (which had NPP) when I did it, and that included eliminating the second set of cats that they added in 2012. It does sound good though, and even better if you gut the LS7 cats.
I don't know if you have modded mufflers but if you don't that IMO really makes a big difference. I have a set of both mufflers (stock and modded) and the modded ones sound much better than the stock Bi Mode muffers.
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Le Mans Master
Joined: Mar 2001
Posts: 8,435
Likes: 3,922
From: Omaha
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
I have an LS2. I did that exhaust, 1.8 rockers and home ported the intake and got 402 rwhp. I got 50ish somewhere, 10 from the intake 15 from the rockers leaves around 25. Someone else on here posted they pulled 30 just from the exhaust so I think on a LS2 that 25-30 is quite doable.
I don't know if you have modded mufflers but if you don't that IMO really makes a big difference. I have a set of both mufflers (stock and modded) and the modded ones sound much better than the stock Bi Mode muffers.
I don't know if you have modded mufflers but if you don't that IMO really makes a big difference. I have a set of both mufflers (stock and modded) and the modded ones sound much better than the stock Bi Mode muffers.
Melting Slicks
Joined: Feb 2001
Posts: 2,015
Likes: 52
From: Largo,Fl fl
I bought a set of npp's that are 2.5 inch, the seller claimed they were from a 2010 gs. I hope they are a direct bolt on for my base 2013. Is there any point in hooking up the vacuum because either you will have them open all the time or closed
Le Mans Master
Joined: Oct 2014
Posts: 8,672
Likes: 2,726
From: Atlanta GA
Most of the time I ride with my NPP'S open but there are times when I want i quiet. On the highway they can drone .
Different people have different opinions on what is tolerable and what is not .
It is nice to have the option
Dave
Race Director
Joined: May 2004
Posts: 16,667
Likes: 1,209
From: Raleigh, NC
St. Jude Donor '15
I have the Z06 setup and when they are open it does drone a bit at lower RPM's, particularly at 60-65mph on the interstate it can be quite annoying. Before I connected them to a vacuum source I just used 5th instead of 6th on the interstate and that was significantly better.
Mine are just hooked straight to a vacuum source. They "open" around -2.5psi on the "boost" scale which works out about right IMO.
Mine are just hooked straight to a vacuum source. They "open" around -2.5psi on the "boost" scale which works out about right IMO.
Le Mans Master
Joined: Aug 2000
Posts: 6,486
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From: Las Vegas NV
If you watch the forum F/S section and on eb*y, very often you can pick up a used C6 perf exhaust system for less than $500 that will bolt right on with no other costs and a minimal amount of work.
Clearly, the NPP is a good system, but if you're looking for something low-cost, there are cheaper options than hoping to luck into a cheap 2008-only NPP set and also an NPP controller.
Clearly, the NPP is a good system, but if you're looking for something low-cost, there are cheaper options than hoping to luck into a cheap 2008-only NPP set and also an NPP controller.
Last edited by Kent1999; Oct 29, 2015 at 03:16 PM.