unfortunately i agree with pahrump... only real way to get beter mpg is deleting the regen mode or the dpf completely. with more power your dpf will fill up with soot faster which means more regen cylcles... you use fuel to burn off the soot in the DPF and so on.... if you want better MPG get a tuner that turns off the regen mode... and if you haven't regeared the truck for the 37's thats another option....