I used to ave. 21.0 tank after tank before ULSD. Then I started doing mods and ULSD hit. I tried to keep track as I made the changes and I replaced the turbo at the time ULSD hit so one of those caused the decrease. Then the Pred shortly after and now I get ~19 no matter which program I use. It's still good for a 4.10 but I wonder if it would be better if I stacked with a pressure box or try the Flux 40 hp. Seems like the P boxes help mpg the most. Craig