It's all about limiting restriction, baby! Open the exhaust, I also run a BHAF in the summer months. Not only does it sound like a logging truck, I am pulling mileage like that of a vehicle half my size. Trust me, for what I paid for it, you can be darn sure I want to raise eye brows and turn heads! :-laf The crotch rockets and rice burners with their coffee can mufflers aren't so tough anymore.