I have tried both the Saito pipe (stock AV10) and the AV7 pipe on my stock AV10 setup. The Saito gives me low end torque, but limits me to 28mph. The AV7 pipe is weak at the low end but then gets me smoothly to 35 mph on flat ground. I am working on a 70cc kit with an awesome intake and case/crank setup, but am not sure what pipe to get.
How well do some of the other pipes work? Can you keep your pedals? How strong are they in the low end and top end? Are you running it with a kit? Whose exhaust reigns supreme?