[townsend]

i was driving my father in-laws '03 silverado 1500 ext. cab 4x4 z71 with the tow package and 4.8l back and forth from phillipsburg to fairfield (150 miles round trip) every day, with the tune, cai, headers and full exhaust i was averaging almost 23-24 babying it windows down no ac cruise set to 70. i couldnt believe it but its true. that truck still gets great mileage now on the highway with meatier tires (21-22mpg) if you baby it at 65. also depends on what gas you run. i dont care what anyone says it does matter, the ethanol crap eats your mileage away. i only run shell now since i worked at a few different gas stations plus drive company vehicles and saw my mileage dissappear with crap gas in my workvan. just throwing it out there.

plus i can still tow a ton of weight with that truck and get not too bad for a little 4.8l fuel mileage

get a tune in it the 5.3l should do better since its more motor for the same weight.