Question about pulley's

Basically right now I've got CAI, Dual exhaust w/h-pipe and a max micro tuner programmer. I'm just looking for a cheap mod for just a little more kick. Pulley's appeal to me but would I run into any power problems as far running my sound system, and would they just help when the ac is on. I've heard a lot of different things about pulley's. Any advice or info would be great. By the way to anybody interested on how my v6 matched up to an 01 GT mustang. Go to Streetfire.net and search 04 v6 mustang bolt on's vs 01 GT. Got any questions reply back.