Drilling three holes on the side that engages (opposite the pinned side) reduces the rotating mass and makes the engine rev to a higher RPM (where it makes more torque)(this is torque multiplication like a torque or stall converter in a real car) before the clutch engages. It seems like a small amount but most would recommend only 2 holes, I had good luck w/3... Remember, that small mass at HI speed makes a big difference (inertia=mass*velocity).........