Ford V10 mileage/power upgrades.

[Rory McNeil]

My tow setup is a 1999 Ford F350 Super Duty Super Cab Dually 2WD, with a 6.8L V10 and ZF 5 speed, with a Dana 80 with 3.73 gears. The truck & trailer combo normally weighs 15,100-15,500 lbs total. The truck is bone stock, other than the factory size tires (215/85R16) were replaced with taller 235/85R16s, and are due for replacement next year. I rarely drive the truck without the trailer attatched, and loaded. When on level ground, it pulls just fine, but it could use some added pulling power while climbing some fairly steep grades, and the gas mileage towing is not that great either. (Imagine that!) I know not many guys tow with gas engine PUs, but the V10 Ford to be rather common on motorhomes. Wondering if anybody has had any positive results with a computer "tune", or bolt on upgrade, like headers, exhaust etc. Or should I just accept the power & fuel economy(?) as it is. I normally only put about 3000 miles a year on it, so spending thousands of dollars to save a few gallons doesn`t seem very cost effective. Also, with the 3.73 gears, I normally tow in 4th gear, except at freeway speed on level ground, don`t know if changing to 4.10 or 4.30s would be worth the expense, but since I will be buying new tires for the truck soon, would going back to the shorter 215/85R16s help much?