I have an 07 VortecMax, quad cab, lifted 6" on 35's and I struggle to get better than 11.5mpg driving 75% city, 25% highway...and that is babying the absolute hell out of the throttle and coasting to stops anytime I have the opportunity...lol. I have the K&N FIPK CAI and a magnaflow cat-back. The ****ty thing IMO is that the truck is only a 4 speed automatic transmission. If it was a 5 or 6 speed I think it'd do a little better, especially on the freeway. I'm contemplating adding a programmer but I really have no idea how to properly program a programmer so I'm thinking of just taking my truck to a shop and having them tune it for me.