custom moby pipes are tricky, cause you either have to find a ball joint (motomatic has had no luck in that dept) or have the whole pipe swing with the engine (in which then you have to make the pipe on the small side).
because of these complications, your better off just getting a doppler or a ninja and calling it a day...I believe that's why Motomatic abandoned the idea. Those pipes are already epic. not much to improve upon really.
how many teeth are on the sprocket on the pulley?