Use Diablew tune here is the link http://www.dslogredux.com/DiabLew_Tune
He is very good. The web page will tell you what you have to do.

Just got a custom tune from 06montess (lew) at diablew tune and I have to say at first i was skeptical figuring that all he was going to do was check the settings I did. Well I put the tune in and gave her a try (07 sierra 2500hd extended cab long bed 4x4 6.0l) and I should have brought a change of ...

Anyone have a sierra 1500 ext cab 4x4 5.3 with 3.73 gears and heavy duty towing package with the diablo tune and if so how much do you tow. I know the manual says 7000# but looking to find out how much it can really tow. I have a dump trailer about 2500# empty and wanted to load it with about 3 ton ...