I put this under your other topic too, "thinking of trading it in..." :
I have a 99 dodge diesel. 4 1/2 inch skyjacker, 315's, and still get about 16-18 mpg around town, and up to 20 on the freeway, very reliable, very loud, and very powerful. Last set of tires (31's) went damn near bald on the rears in about 15K miles. Not a real great tire, and poor rotation on my part, but still shows the trucks torque. Banks power pack can put it up to just over 300 horses, and between 650 and 700 ft-lbs of torque.