I bought one a while back, never got the chance to use it though. couldn't route it with the provided piping, wouldnt clear the pedals, wouldnt go around the frame, but I connected it all anyway and went for a test ride without pedaling. I gotta say, the volume was comparable to the stock motor, but I didnt find any advantage, then again, I only got a block away before the copper slipped out of the rubber tubes and fell off, never to be seen again. Now I cant find any rubber that will fit. so its been sitting here... Found a flex pipe that fit, but it leaks like crazy., been considering making my own, but lack skills and tools. I bought some more copper, but I cant find any rubber to fit. I'm just thankful I used the exhaust hanger, that saved the chamber from being lost as well.
