I have a superchip tuner and it gets me about another 2 mpg's in my '05 6.0. Also have the 4" turbo back and AFE intake. I tow a 35' travel trailer, about 9k lbs empty. I get around 13-14 towing. I traveled from St. louis to Brunswick Ga to Mt. Airy North Carolina and back to STL last Thanksgiving (3400) miles. I spent about 850.00 in fuel for the trip. That was at about 3.00 per gallon at the time. I just bought a ScanGaugeII and like it alot. I can watch % power used and actual mpg's as well as several other readings. I noticed, when pulling my enclosed utility trailer that just slight variations in pedal pressure changed that % power used and MPG's drastically without much speed loss. I am leaving tommorow on a trip with the camper. I think that by monitoring this gauge and changing my driving a little will help overall fuel usage for the trip. I will let everyone know.