technical exhaust question
Thread Starter
Pro
Joined: Mar 2006
Posts: 643
Likes: 70
From: EAST TEXAS
technical exhaust question
I am considering putting the stock NPP exhaust mufflers and an aftermarket control system on my 2006 cooupe. But I have one concern I hope can be answered by someone knowledgeble on the subject. As I understand, on the stock NPP system, one flap on each muffler stays shut until a certain rpm is reached at which time these open, which results in a total of four openings for the exhaust. Also, if an aftermarket control system is used, the two flaps can be opened at any rpm for a total of four openings for better sound. But what about going the other way? For example, what if the driver wants the sysem closed in order to be in the "quiet mode" and then runs the engine up to a high rpm at WOT? Would this result in any harmful backpressure or lack of power due to there being only two outlets for the exhaust?
Race Director
Joined: Jun 2005
Posts: 10,909
Likes: 2,701
From: Phila Suburbs 2023 C8 & 2013 650ix
GM says the NPP system when open at full power gives you 6 HP additional over the stock system. There will be no harmful back pressure with the system closed and you'll lose 6 HP. Nothing to worry about.
Pro
Joined: Oct 2008
Posts: 735
Likes: 3
From: New Harmony IN
St. Jude Donor '09
I am considering putting the stock NPP exhaust mufflers and an aftermarket control system on my 2006 cooupe. But I have one concern I hope can be answered by someone knowledgeble on the subject. As I understand, on the stock NPP system, one flap on each muffler stays shut until a certain rpm is reached at which time these open, which results in a total of four openings for the exhaust. Also, if an aftermarket control system is used, the two flaps can be opened at any rpm for a total of four openings for better sound. But what about going the other way? For example, what if the driver wants the sysem closed in order to be in the "quiet mode" and then runs the engine up to a high rpm at WOT? Would this result in any harmful backpressure or lack of power due to there being only two outlets for the exhaust?
Pro
Joined: Oct 2008
Posts: 735
Likes: 3
From: New Harmony IN
St. Jude Donor '09
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