i have the ASP one on my truck. there was definately a little more kick after i got it installed especailly off the line. i got mine pretty cheap. if i had to pay full price i'm not sure if i would have gotten it or saved up for gears or a cam. it can get a little annoying in town when it is hot out that the a/c isn't as cold but once you get it over 900 rpm's it comes back up to normal
Yeah the electric fan is the direction that I am going it is a more mechaically sound modification i think. Personally i think it will yeild more power. Air Ram claims 10 RWHP and 2 MPG on a 4.7. With the pulley I'm not sure slowing down the water pump, manual fan, a/c, and power steering is a good idea in a truck that I tow with. This is just my opinion though.