I'm a mod newbie so someone pls explain how lighter pulleys increase max HP. I understand how they improve transient response via the reduced inertia during throttle changes and could show up on a dyno run during accel's but during steady state conditions I don't see it.

 

The gains come from the underdrive effect on the the accessories. For example a smaller crank pulley will turn your water pump, alternator, A/C compressor , PS pump slower and hence reduce the drag on the crank. So as far as new pulleys go, the crank pulley itself provides the main power improvement. The others pulleys such as alternator are mostly cosmetic. The weight reduction itself has a minimal effect in performance. and is overrated via "rice math".

 

Dude your Z looks tight! Very nice, may I recomend a g35 spoiler?