A de-restricted exhaust is really all you need on a stock cylinder from what I've learned. Aftermarket exhausts are really only for kitted big bore cylinders or seriously ported 50cc cylinders from what I have found. The stock exhaust flow is really not that bad, so getting an aftermarket exhaust like the ninja or one of the doppler pipes really won't change the performance of a stock cylinder. If anything it'll give you more problems and grief than it's worth. If you are comfortable porting the cylinder on yours, then you can consider the aftermarket pipes, but a de-restricted stock pipe will probably be fine. If you want more power (who doesn't?) then mess around with the jetting. modifying the variator may also help a lil bit too, there are plenty of threads discussing how to tune those for better power distribution. Also, I'm curious, what method did you use to derestrict yours? I'm going to derestrict my stock cashew exhaust soon and I'm curious as to what works best.