I found the trick to great gas mileage with my Hummer. I let it sit in the garage more, but then I do drive I have a smile with every drop of gas it takes!
But I'm thinking of a Magnaflow exhaust and a Volant air cleaner kit. I'm not shooting for more mileage, Just cooler sound. I knew it was a gas hog than I bought it but it's one of the funist truck to drive.