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Old 05-29-2014, 09:18 AM   #7
ST1LE


 
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Drives: E92 BMW M3
Join Date: Oct 2012
Location: Houston
Posts: 4,496
Quote:
Originally Posted by Nate76 View Post
What's NPP? Could someone also please explain the dual mode and how is sounds. Also is it available on non OEM exhaust? What I'm looking for quad tips, a nice low rumbling sound and not too much cabin noise except when I'm really giving her gas. Any ideas/comments?

NPP is the factory code for the OEM dual mode exhaust. The dual mode uses the ECM and vaccum lines running to the engine to open and close flaps on the exhaust..one side is straight through and the other is through a muffler. This is NOT easy to do after the fact. I think Billy Boat has a dual mode exhaust, but I am not sure and cant think of how that works after the fact either.
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