Phil,
My first recommendation, besides obviouslt telling him to take it easier on the throttle, would be to install a set of guages. It becomes obvious when you are pushing the engine harder than necessary when you see that boost ramp up and the EGT's climb. Once he sees that, it might help him change his ways, then go for the custom tune. Also, I would hard wire his to the economy tow mode so he can't play with the performance setting because he would love that power too much to stay out of it
\'05 Chevy 2500 HD LS CC/LB 4x4 D/A, Century Cap, Line-X Spray on bedliner, SS Nerf Bars, Lund Bug Deflector, 235/85R16E LTX M/S II, Kennedy Custom ECM Tune, Uni-filter, EGT/Pyro & Boost Guages