Just as an observation, I had a TJ with the 4cyl on stock tires and it got schite for gas milage. My XJ with 32's and the 4.0 gets much better milage because the larger motor doesnt have to work as hard. I had to flog the bloody hell out of that motor just to get it out of its own tracks. I think 12mpg was about the best i ever got. Ask Cal about this one.