HPM,

Yes they do vibrate.. so do the stock 90's. The stock bars are also crap..! you can put a set of good bars on it like ATV Four Play or Flexx bars and that should do away with your vibration... A better quality anti vibe stem may help also. I am not sure if a built motor vibrates as much since we have never had one in a chassis with stock bars on it. More parts are generally available in the 90cc range because that's usually what most race classes allow. There are some larger 95 and 98cc kits around but not very popular in the US. The stock pipe is pretty good for a stock motor. If you want to make it faster I would start with a Max Speed kit from gforce. Porting the stock cast iron cylinders also works well. To take advantage of most performance pipes out there you need to create more RPM's and you cant do that with a stock ignition.. so a pvl would be needed. So if you want a really fast reliable stocker: Over Range kit, ported cylinder, pvl, exhaust and possibly a good intake and reeds... but IMO I will say in stock form a properly setup apex will be 10x the machine the LT80 was.