slow down to 65 mph and accelerate easier meaning use less throttle. I would bet you will crack 20mpg if not higher. slowing down is one of the easiest ways to get better fuel economy. my buddy has a 6.4 extended cab short bed with 3.73 gears and he just got back from a trip from ct to nc and got 26 mpg hand calculated. and consistently gets 25-26mpg in the 275 tune egr delete and dpf delete as well. he also bought his truck new and only has 45000 miles on it.