I noticed a very slight increase in mileage with my challenge xpipe but that quickly went in the tank with my tune. No one is getting 29 or 31 in these cars. Low 20s is about it if all freeway.
02 Tiag e46 M3|6MT|GC plates|MCS c.o.|GC race control arms|GC bushings & bearings|BW eng. & tran. mounts|subframe kit|BW race shifter|BW Jaffster knob|Euro header|Eisenmann sport|K&N c.a.i.|Seibon CF hood|CSL bumper|CSL brakes|RS19s|SS lines|half cage|Recaro profi|Profi 2 harness|race pulleys|BMWpedals|Apex studs|1995 Ford Probe gt chump car|