THE XMR IS A NICE MACHINE WITH LOTS OF POTENTIAL. WE USE A 3 WEIGHT ADJUSTABLE SET UP INCLUDING BOTH PRIMARY AND SECONDARY SPRINGS, AND A SHIM PACK TO ADJUST ENGAGEMENT RPM'S. THIS KIT WILL IMPROVE ACCELERATION ACROSS THE ENTIRE SHIFT AND IMPROVE BELT GRIP TO HELP REDUCE HEAT. ITS A GREAT CHOICE FOR MOST MUD TIRES UP TO 32". FOR LARGER THAN 32" TIRES WE RECOMMEND THE REV X COMPLETE PRIMARY CLUTCH.