Here are the kit components in the sheave upgrade kit that Rigid sells. It includes a machined sheave, new heavier weights, Teflon weight sleeves, and a stiffer spring to be placed behind the secondary (driven) pulley. The kit also includes a replacement set of clutch springs that can be installed as an option. This mod requires additional work to gain access to the wet clutch portion of the engine. The new springs increase engine stall speed (point of clutch engagement) from about 1300 rpm to about 2000 rpm to allow the engine to rev higher before the Rhino takes off.