I put a harley softail muffler on mine yesterday. My dad and I got 'em for $20 and paid another $25 to have the crossover cut off and filled in. $45 and 3 hours later, it sounds like an angry lawnmower, but in a good way.
If you're prepared, this could be a one hour job. If unprepared, expect several hours of frustration. (I did it the hard way.
) It sounds sweet, but it might not be your thing.