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      06-24-2011, 03:44 PM   #6
rockd's Avatar

Drives: '11 Z4 35i M-Sport 6MT
Join Date: Apr 2009
Location: San Francisco

iTrader: (11)

Originally Posted by richpuer View Post
Ok so via the other thread I kno the challenge street is capable of this BUT are there any other options that are bolt on and don't require cutting oem pipes? I want to keep oem ones just in case I need to swap it out in the future. What options do I have without going custom or cutting?
Every x-pipe that is bolt-on will either eliminate or replace the primary cats (due to the primary cats and secondary cats being one piece). Eliminating them will definitely trigger a CEL, and replacing them with HFC's will *most likely* cause a CEL eventually.

The only way to ensure no CEL and to pass OBD2 readiness tests is to NOT touch the primary cats, which means cutting the factory exhaust system.

PM me if you have any more qs.