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      11-04-2011, 03:33 PM   #66
Major General

Drives: 08 E90 M3, 99 E36 M3 Turbo
Join Date: Feb 2011
Location: Concord, NH

iTrader: (3)

If you don't want to change the software to accomodate catless running, then you should stick with a pipe that eliminates just one set of cats or that substitutes high flow cats for the one set that remains. No CEL, emissions passability, substantial power gains, and closer to the ability of the stock ECU to adapt to take advantage of the improved flow. You can find dynos for these kinds of x pipes with some searching. Fabspeed makes one, Sosi makes one, Turner sells cat delete pipes for the stock exhaust, AA and Challenge and Akrapovic and others sell complete pipes with high flow cats, etc.