My truck is an '04 Sierra 2WD 5.3L, 4L60E, 3.73 gears. The only add-on is an Edelbrock Cat-back exhaust. I just got back from a trip from South Central Texas to Northeast Louisiana and back. According to the on-board "computer" I averaged 20.4 MPG and figuring it "the old fashioned way" I get
19.9 MPG. This is a lot better than I expected. There were six of us crammed in the cab (2 adults, 4 kids) and I was hauling about 600 lbs. in the bed. What kind of mileage are you guys getting out there?Cheers, Kyle