The stock pulley is heavy for a reason. Its mad of 2 major parts, the inside part that bolts to the crank, and the outer ring thats hedl on with a rubber layer.

This acts as a harmonic balancer, or, more correctly harmonic dampner. I would think twice about the effects of messing with that. I have seen balancer/dampner assemblys add HP on the dyno on V8 engines. at that small diameter the change in rotational mass is not that great.

John C.