I wanted to add this: some people may get more or even less gains in mpg depending upon their driving style, weather conditions, and even their trucks setup. With a tuner, throttle body spacer, good air intake, and cat back exhaust you can gain up to 20% or more mph. But everything must work together to get those gains. Someone that drives like a maniac may never see any mph gains, and yet someone that drives concervatively can see much better gains. Also your transmission ahs a large impact upon mph also. A manual transmission can get better mph than an automatic, depending upon how it is driven. What I got with my truck is not typical and should only be used as an example of what could be gotten under the best circumstances. Nottoo mention at this moment the Quad Cab is the family car and not driven hard (having 3 kids in your truck makes you slow down).