I have an 07 LBZ, stock other than a K&N filter and LT 285's. I get 14 mpg around town, I accelerate slow (seldom get above 2000 rpm's), coast to a stop and very little idle time. My wife always busts my chops for driving so slow. About 4-5 times a year I pull and 12k lbs 5th wheel and get 9-10 mpg, I live in Florida (flat land). I hear some say they get in the low to mid 20's mpg and 12-15 mpg towing with stock set ups. I would have see it to believe it. From what I have read on this forum most agree the cold air and exhaust are a waste of money, the tuners work but they void warranty. Sounds like Mr. Kennedy has the setup's but I don't know what I want to do, all the info is confussing and sometimes contradicting. So good luck.