I got a 125cc kit for my X18, which takes you from 107cc to 114cc and it has a raised piston w/ valve relief. A 22mm carb and a good exhaust and an hp coil, and racing CDI, would probably do the trick. You would have to empty the eng cases and bore the cylinder mount hole in the block to go 125-160cc. TBoltUSA online has all kinds of hop up stuff.