[WestButteTruck]

Hmmmm, if you are getting that good of mileage, I'd be reluctant to change anything. However, if you decide to, have someone do a custom tune for your vehicle. I had BlackBear Performance do a chip for mine and so far it's been good. I didn't see huge mileage gains, but probably an honest 1.5-2 mpg difference from stock. I'll see an average of 15 on the highway at 70-75. Not the greatest, but better than 12-13 I guess. Power and performance were improved as well.