Peugeot pipes seem to be the best for fit, because they mount flat, have flex built in that can absorb most of the vibration, and there is a HUGE variety.
The gianelli for sachs cracks from vibration pretty easily, it's supposed to be a mid range pipe. It's plenty fast on the 80cc reedvalve kit. I haven't tried any other pipes yet because I'm broker than broke and have been for a damn long time.
Right now, my clutch set up is 7 piece, with 3 metal/fiber plates and 4 thin metal plates. Torque, large nut and threadlock came undone. Now, I've got a thinner nut, torqued down, threadlocked, with a bicycle axle nut (m10x1) double nutted, torqued and peened. We'll see how long that holds.