We'll know about the underdrive pulley next week. Mine is supposed to be delivered UPS friday. I'll hopefully have it on this weekend, track tested thursday and dyno next saturday. Part of my deal with them is to post my results so I should have a good comparison of everything- idle, idle w/ ac, idle w/ stereo, hp, track time, etc.
I would reconmend a VELOCITY PERFORMANCE MODULE that delivers 20 horsepower and cost less than $30.00 and will take you about 10 minutes to install. I just purchased the module and I think its the best thing , so for more info on this product just type in velocity in the search-Goodluck NaS.
I didn't have any trouble finding a set of gears reasonable. I have 4:10s and a tracloc diff in my truck waiting for a shop to say yes. The problem is that noone wants to install it since they did not order it. And if they say they will it's going to cost me close to $500 labor- AAARRRGGGGHHHH, that's insane!!
My pulley is being delivered tomorrow so we'll have those numbers soon enuff. I would do the electric fan at the same time but the terms of getting the pulley is to test it and only it and post findings.