Here is a good thread you should read
Banks VS Blown Head Gasket
I'd make sure that you want to chance stretching the head studs, thats what the 6.0's are prone to especially since it is an 03'
Only tune that is going to billow the smoke is an agressive tune. (black smoke is unburnt fuel)
Along with the unburnt fuel is ALOT of boost.
A "safe" tune will smoke, but not near as much as the agressive.
btw here is some advice, we hear all the excuses not to use the search button, u can think that..just dont say it in a post thats a quick way to get no responses.
Dont just jump in with no research and get a tuner, you will be sorry.
Happy Modding