with our testing that we have done, with our clutch kit (springs and weights) the we supply the best belt for the kit. It is rated for 125 HP, it is 8 ply kevlar constrution. Hooks up great! As far as testing against the factory belt, we were pushing this thing HARD, and exploded the factory belt. we havent had an issue with the extreme duty belts. Not to say that we wont, its just that we havent. All belts wear out and ALOT of it is driver error when it comes to Premature wear. If any of you have been an avide snowmobiler, you know how to drive a CVT Properly. Not saying the others dont, but alot of people forget that there is a LOW Gear. Use it when you are going slow or technical and you will keep the belt alive ALOT longer.