I drive a '98 TJ 2.5L auto, 31/10.50s. Putting on a TB spacer (and a properly geared speedo gear) was the smartest thing I did. Mileage went from 12.1 to 17.9, (50% increase) the shifts were cleaner and all-around drivability is just excellent. I live in S.W. Florida, so 'trails' consist of running the canal banks at night, spotting gators with my grandsons.
hunter