you could be expecting too much also..in my opinion id get a dyno tune, that way you know your running as much timing as possible without knock and running the proper a/f ratio's..what gears do you have?

 

3:42's

 

IMO you are expecting too much out of a stock 5.3, the 3.42s are going to kill your low end. If you really want the best you can get, call up Wheatly(if you can get ahold of him) and he will take it as far as it can go, plus he is local to you.

 

Hard to beat a live tune. Not knocking wait4me, but Charlie riding in the truck is going to get it alot more dialed in then Jesse can from a couple states away.