this is my opinion: DONT PUT JUST THE EXHAUST ON THE BIKE!!! i work at a harley dealership and i never sell someone an exhaust without remaping the fuel injection and installing a high flow air cleaner. the race kit offered by buell is definitely the way to go (that is if you want to use buell parts). think of it this way...the exhaust is more free flowing than stock, this means more air is going out of the motor. you need more air going into the motor becuase of this...thats why you need the high flow air cleaner. with more air going in and out of the motor you need more fuel...thats where the tuner comes in. if you install just the muffler it will run worse than stock. if you have any more questions feel free to email me.