A higher compression piston will give you some more power. How much? I can't say that. I haven't done that one yet. If you go to a stock first Gen. 200X compression ratio at about 9.5:1 (I think) you'll be fine. I've heard that if you go much higher than 10:1, they have had issues with the pull rope breaking. I don't know if their decomp was working right or not. An aftermarket exhaust will be costly if you can find one. It will give you more power too. I don't believe that there is any performance heads available for these engines. I've heard that porting and polishing, or just a good polish to clean up the ports makes a fair improvement. Any power gains will need to have more rejetting done as well.