My '01 F4i runs real rich. Everytime I get off my bike, I smell like exhaust with an overly rich fuel mixture. I checked my mileage last tank and only got 35mpg, which seems pretty low to me. I have heard that aftermarket pipes will cause the bike to run rich. I have a D&D slip-on, so I'm assuming that this is my problem. So, is there anything I can do to remedy this problem?