ben99
New member
I have an 05, 2500, 4dr, 4x4, srw, flatbed with 110xxx. I used to get 18.5 mpg on the hwy at 70mph and now I'm only getting 15.4. hand calculated on long highway only trips. I have 4in exaust, egr blockoff, afe turbo inlet, airdog 150, and ppe tuner on 90hp. Synthetic fluids in the entire truck. I cant find any reason for the drop in mileage, no codes, no boost leaks, etc. Is there anything else I'm not looking at? Thanks!
