The closed mode is almost, but not quite as quiet as the stock mufflers.
Npp vs bi-mode
Team Owner
Joined: May 2004
Posts: 82,175
Likes: 1,319
From: McKinney TX
St. Jude Donor '21-'22-'23-'24
I think what you're calling bi-mode exhaust is what GM actually calls dual-mode exhaust. NPP is just the RPO for it. Here's what the 2008 order guide says about NPP.
NEW! Exhaust, dual-mode, performance,
increases horsepower, adds 6 hp, aggressive
exhaust sound
increases horsepower, adds 6 hp, aggressive
exhaust sound
Instructor
Joined: Jan 2011
Posts: 214
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From: Des Moines, Iowa
Bi-mode comes on the z06 and has 3" pipes. NPP is an option on the non z06 cars and has 2.5" piping. Other than that they basically operate the same. You will have to get a control box for the vacuum actuators if you car didn't come with one from the factory.
Thread Starter
Burning Brakes
Joined: Aug 2008
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From: Katy/Houston Texas
Thanks that's exactly what I needed to know.
Supporting Vendor
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From: Pensacola Florida GO GATORS!!! www.rlsebring.com www.c6c7vette.com
St. Jude Donor '17
The tone of the two exhaust are slightly different as well. I started witht he stock muffler mod and that led to hthe Z06 muff then modded those then led to the NPP which I still have and love.
If you get a chance to listen to both and make the decision. It's nice to be a little loud most of the time then hit the button for quite when needed or wanted...
If you get a chance to listen to both and make the decision. It's nice to be a little loud most of the time then hit the button for quite when needed or wanted...
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C6 of Year Finalist (performance mods) 2019
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