I dont know about the 6.0 heads for one reason. I know a guy that put a Procharger on his 5.3 turned the boost up to see how much hp he could get and burnt up the 7 piston. Then he bought the Ligenfelter 6.0 ported heads that were very expensive a new cam and pistons. He put the 6.0 heads on and it wasnt making the kind of power he thought it should. Then he re installed the stock heads and made more power with them. I dont know why if someone knows please inform me. BTW he now makes 550rwhp with a ex cab 5.3

 

There could have been way to many variables in yor buds truck that are not even thought of here. It's a fact that stock 6.0 heads outflow the 5.3 heads. It will also lower the compression ratio slightly to make more boost safer.

Those Lingenfelter heads could have bene poorly ported or something like that. I was talking about stock heads.

 

intake flow isnt as important on fi as n/a, i think you would be wasting your money on a set of heads, you would see more gain from a camswap and better tuning, as far as tuning makeing burnt intake valves i dont see how, the reason they burnt was from the o/h problem and the pressurized cold air from the s/c, warped the valve stem.

 

Cam and tuning first. I would still look at the #317 6.0L heads tho....

 

I wouldn't do 317 6L heads on a 5.3 either, I'd go with stock LS6 heads. You'd drop the CR to just over 9:1, have much better flow, and have a great combustion chamber design. Those items will help you resist detonation, yet it should still be plenty responsive.