Originally Posted by Ultimateride14
My thought would be is if you gain Hp (within a certain severity of modification) You should gain mileage. The more power your motor has the easier it is to move the truck. So unless you have a crazy rich tune. Any moderate gain in power should give you better mileage.
I think you just about nailed it. Unless you are creating more power by using more fuel (larger injectors, larger displacement, and even turbo or S/C) then if you gain more power you should gain mileage.
How hard is the installation of a programmer, and how exactly do they work?