I recently bought a 2006 cummins, It has a 5" lift, 35s, efi live, and an intake horn. I am getting around 12 mpg (calculated at pump). I know the tires don't help but I should be getting better than that. It doesn't matter what tune I run or how nice I drive it. I am lucky to get 300 miles to a tank. And the truck is constantly hazing black out of the tail pipe, even when i return to stock. There are no engine codes and data log shows all injectors are firing fine. I ran a tank of additive and it didn't seem to help. Any information or suggestions would be awesome! Thanks!