Hi to all , I did that to my muffler and it did indeed pick up some power and its only a little louder. I think maybe 1 or 1 1/2 hp gain but not much more. Mike at Simpsons motorbikes has a more tuned exaust you can buy that should make a bigger difference if you have the cash. He also sells carbs and some carb parts and soon will have the elusive 36 tooth sprocket that will allow for speeds in the 40 mph range.I plan on getting the sprocket when they come out . That should be a blast to cruze at 35 - 40. Right now mine will do 35 but its crusing speed is more like 25 - 30. Well good luck whatever you do .......Tom in VW