I ran a 3" on my 5.3 until I swapped in my new engine without any problems, but thats the smallest I would recommended without going to an 8 rib setup.

 

I just need to find a pulley and go with it i guess. So it will make a day and night difference with LT and new pulley. It makes me very anxious to throw both on. I just need to actually sit down and buy them now. lol