NPP C6 performance
Thread Starter
Instructor
Joined: Jul 2012
Posts: 125
Likes: 9
From: Phoenix Arizona
NPP C6 performance
I really tried to search the forums for this but couldn't find a definitive answer. I have a bone stock 2008 bone stock C6 and putting stock Z06 manifolds, cats, H-pipe and trying to decide if to leave the stock NPP C6 2.5" axle back exhaust in place.
This is not a sound issue. Performance wise is there a loss going back to 2.5" exhaust that far back in the system.
Yes I know headers, a cam, turbo, blower, will produce more power but for a stock motor with Z06 exhaust manifolds, Z06 cats, Z06 H-pipe is there any performance gains from leaving the stock C6 NPP 2.5" system in place?
This is not a sound issue. Performance wise is there a loss going back to 2.5" exhaust that far back in the system.
Yes I know headers, a cam, turbo, blower, will produce more power but for a stock motor with Z06 exhaust manifolds, Z06 cats, Z06 H-pipe is there any performance gains from leaving the stock C6 NPP 2.5" system in place?
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,106
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
Yes. There is an advantage to keeping the 2.5" over-the-axle pipe to the mufflers on both LS2 and LS3 cars. Since those engines are smaller and don't rev as high as the Z06, the gases cool quicker and lose velocity when dumped into 3" pipes. Cut about a foot off the back end of the H-pipe and reduce it to 2.5" to mate up with your current stock NPP pipes. By reducing the size at that point, it will help maintain the velocity.
I believe my car is the only LS2/3 in the 10's without headers and this is one reason why.
I believe my car is the only LS2/3 in the 10's without headers and this is one reason why.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,106
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
There are still power gains for a LS3 in the 12-18HP range by using the Z06 exhaust manifolds back to the H-pipe, primarily due to the better flowing system, not necessarily the pipe size. I would guess the next mod would be a CAI to free up incoming airflow.
Le Mans Master
Joined: May 2011
Posts: 5,022
Likes: 18
From: Tampa FL (formerly Justinjor)
Tech Contributor
St. Jude Donor '11-'12-'13-'14
Interesting info Tom...
I wonder if that's part of the reason my car made more power than most cam-only LS3s(517whp)? I have a 2.5" x pipe instead of the traditional 3"
I wonder if that's part of the reason my car made more power than most cam-only LS3s(517whp)? I have a 2.5" x pipe instead of the traditional 3"
Drifting
Joined: Feb 2012
Posts: 1,255
Likes: 66
From: San Luis Obispo, California
Subscribed..I'm in CA., bone stock '12 GS 1LT 6spd, & headers aren't an option out here, so I'm seriously considering factory LS7 headers, with an LS7 mid/Xpipe necked down into my stock 2.5" NPP cat back system.
It sounds like I might see an addtl 12-18 RWHP? I'm wondering if I would need a tune, or could/should I leave the tune stock & not jeopardize my warranty?
It sounds like I might see an addtl 12-18 RWHP? I'm wondering if I would need a tune, or could/should I leave the tune stock & not jeopardize my warranty?
Race Director
Joined: Mar 2005
Posts: 10,399
Likes: 25
From: Austin Texas
Thw Z06 axleback already goes down to 2.5" at the muffler entrance so you are only losing about 18" of 3.0" pipe. There won't be any noticable difference.
Your choice, buy a Z06 axleback or pay to reduce the end of the Z06 midpipe to 2.5" to accept the NPP axleback.
Your choice, buy a Z06 axleback or pay to reduce the end of the Z06 midpipe to 2.5" to accept the NPP axleback.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,106
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
Subscribed..I'm in CA., bone stock '12 GS 1LT 6spd, & headers aren't an option out here, so I'm seriously considering factory LS7 headers, with an LS7 mid/Xpipe necked down into my stock 2.5" NPP cat back system.
It sounds like I might see an addtl 12-18 RWHP? I'm wondering if I would need a tune, or could/should I leave the tune stock & not jeopardize my warranty?
It sounds like I might see an addtl 12-18 RWHP? I'm wondering if I would need a tune, or could/should I leave the tune stock & not jeopardize my warranty?
You can keep your stock tune.
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Drifting
Joined: Feb 2012
Posts: 1,255
Likes: 66
From: San Luis Obispo, California
Thanks HOXXOH, much obliged. I may just pick up a set of Z06 headers with an already necked-down 2.5" x-pipe (at the front, before the X section), as the guy already had it on his '08 LS3. I'm told (A&A, etc) that it wouldn't have to have a tune either.
I'm just trying to decide if the $$ & work invested would be worth the potential hassles for only 10-20 extra hp/Tq. Feedback seems to indicate I wouldn't get much, if any, sound increase either.
I'm just trying to decide if the $$ & work invested would be worth the potential hassles for only 10-20 extra hp/Tq. Feedback seems to indicate I wouldn't get much, if any, sound increase either.