Finally a new truck.

Yes Mooring, I've been in a tuned diesel, if by tuned you mean 'bombed' or chipped. I worked with 2 guys who have the exact same truck as mine; year, model, tranny, etc. They put some sort of Bully Dog thing in them. With stick shift tannys, I can't see much difference when no load is in the truck. I can only shift so fast and the engine spins up as quick with as without in an empty truck from a dead stop. Since I'm able to do 70mph+ up any of the grades here crossing the sierras in CA with my camper and pulling my boat, why bother with the expense and voiding of the warranty? Also, here in CA they smog check diesel trucks. First thing they check is if it's chipped and even check to see if it's ever been chipped even if the chip was removed. A simple air cleaner upgrade is cause to void the warranty. If I were to do anything to my diesel, I'd get the air cleaner to be less restrictive and loose the muffler and CAT converter. I think just letting the motor breath would help enough for anything I would want above stock. I did make one small change; I advanced the timing by 2*. It helps a bit with fuel economy and a little more HP to make up the difference in the taller profile tires I've changed to.