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      07-29-2010, 12:39 PM   #9
Private First Class

Drives: '14 335i M-sport
Join Date: Jul 2010
Location: So Cal

Posts: 150
iTrader: (1)

Yeah, this is definitely aftermarket. It's not just a flap that opens within the muffler to make it louder (like in a corvette), these valves bypass the mufflers all together. Check out my buddies build thread, you can see his install and videos for his exhaust cut-outs.