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Old 11-20-2012, 12:19 PM   #164
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Join Date: Apr 2012
Location: Vancouver, wa
Posts: 251
My Ride: 2005 325i SULEV
Originally Posted by briangl92 View Post
I don't have a diagram but the headers have unique cats, then another set of cats then the 330 rear muffler with the active exhaust flap.

An M54B25 has cats in the headers, a set of resonators, then a muffler.

Both run dual pipes all the way back to the muffler.
So if I was to run aftermarket headers, would I run into emissions problems with the second set of cats?
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