I have an 04 6.0 super cab 4x4 bone stock everything it got 15mph average. I then gutted my kitty and put a Diablosport in, I know no lectures, (I haven't had 1 problem with it) I rearely tow, so mileage is checked not towing. on tow setting it gets 18-19 mpg, economy/performance setting, same 18-19mpg, extreme setting gets 16-17 but the tranny shifts awful and never seems to adapt, on tow setting the truck has almost the same throttle response, but doesn't smoke like the extreme setting and gets better mileage and the tranny is butter smooth like stock, I'll leave it on the tow setting from now on......