I am new to this site, been wheeling all my life, but never dealt with a CVT. Just bought an 05 grizzly 660, and I would like to get a clutch sheave mod to help turn my 27" tires/wheels. I have narrowed it down to Coop, JBS and airdam. I ride rocky up hills and mud, along with access roads, so I need it to be an all around quad. Can anyone help me make this decision? I can find information on each, but not much that compares all 3. Any help would be very much appreciated. I am interested in results, not arguments.. Please!