I put a lift and some 35's on my truck and destroyed the fuel milage! Lost about 4 mpg AND the power it cost me almost had me thinking of taking all that off . So, that's not going to cut it! Got A SCT livewire tuner from Innovative diesel and all I have to say is DAMN!! Unreal how much difference it makes... I tried each canned tune tow(65 hp)street(85) and the performance tune (120) PLUS I have a 140 on there too along with two other custom tunes from them.... I went playing and so far on the 120, seem the fuel mileage is better than it was stock!