Well I've tried my pipe on my OS 32sx and Enya 35X (the same pipe fits both engines) and it really did make a difference. There are two pipes you can get: Power pipe, for top end performance (i think) and the throttle pipe, for midrange and some top end performance. I'm running 20% nitro now too and I would say I'm getting about 10-15% more power, bottom end is a lot smoother too and I can hang my standard cougar on about 1/5th throttle.
Prices are around £30-60 for this size.

Hope this helps


Dean