Since owning a Ct4s, i have gone thru about 10 side belts. And pretty much every single peice on the drivetrain has faulted except the diffs. I have replaced the plastic 17t with metal ones. Still chews belts. Get a tensioner aswell and tighten right up. This will help a little. The competion drivetrain is still plastic. Instead of using the plastic 16t, u can modify the metal 17t side gears to fit front and rear. Just linish it down like 1 or 2 mm. Fits perfect. And takes all the slack out of the dodgy belts. My front belt is actually pretty good. The front tension is wound as far out as possibly, cause the 17t really takes up the slack nicely. Fit a 177t belt on the rear, dunno if thats the same as the compition kit? Fits nice. No slack. Im sorta trying to fit a HPI 180t belt on the side with a mod mentioned here in the forums. CEN belts are CHEAP. If there was quality belts for the ct4s, this would be a much better car. The belts are your worst enemy!! And plastic bits....