I am also interested in the clutch drilling, was thinking of this yrs. ago but thought it would blow to pieces especially the primary! I bet the mfgr's take a close look at that? I was thinking of lightening holes all around the periphery of the secondary since you have more contact surface and the belt will be mainly below that point in a hurry. Basically spiral downward with progressively larger spacing to not loose contact surface when geared up! Just think how much outer weight could be lost on a 11" clutch when gearing up towards the bottom? Kinda like the small brake rotor they went with this yr. to reduce reciprocating mass at the perimeter. It makes the belt drive look like it was responsible for the power/response improvement, but I bet the rotor did more for it than we are led to believe? Mike