He needs at least the whole rotor pack as the gears press on the rotors. For the Venom Cooler they just need the snout or front drive assy.
Wotgtp you are spot on w/your analysis of how and why it works. Yes you can just drop pulleys, but the gear whine is music to my ears.
50% increase in boost so stock we are at 9 lbs? That would put me at 13.5 psi w/stock pulley I believe w/the big stock 3.8 on there.
smaller pulleys also create belt slip situations, so it's good to have a solution that lets you use pulleys that will have a little wrap to them yet.