With no supporting mods, no smaller then a 3.5" and even then it'* hard to say. you can drop to a 3.1" with stock MAF and injectors. But you need a lot of supporting mods to get to that point. If you want to drop pulley size I suggest getting a MPS and then you can change pulleys real easy. Start with a 3.5, then add other mods like headers etc.
thats the plan i've been reading alot of what has been done the only bad thing is down here you cant find parts or shop that will do alot of upgrades i can do most of them myself but somethings i want to be safe and pay to have it done right