OK ,here's the "readers digest" version. A tunable pipe is on that you can adjust to your motor. If you do desire to modify your motor from the state from which you bolted your pipe on you can set your pipe to the motor. This may save you a few bucks..I'd call that a pro...unless you've got stacks of green to throw at the bike's pipe instead of putting it to better use. The only other con that I can think of is that the tunable pipe may or may not work on your highly modified motor. I'd buy the Pro Pipe and have done so in the past. They sound great, work great, will adapt to modifed motors. The con to this pipe is that it doesn't look great and that the big can will discolour a little..other than that..your call.
