I removed the charcoal filter when I installed the new K&N and swoop scoops. A nice performance improvement from stock, but very little sound difference. May be a bit early to tell, but I believe that I improved by about 1.0 mpg.
http://www.e90post.com/forums/showth...79#post3572879
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Cobb AP v3 - Wedge tuned, Cobb FMIC, AR catted DP's, Dinan Stage 2 suspension, Koni Yellows, M3 control arms and strut brace, BMS chargepipe, BMS OCC, BMS Sport Oil Cooler Valve, BMS CDV, RB Turbo PCV, aFe Stage 2 SI intake w/scoops