A lot of it depends on what what gears you're running. 3.31 or 3.55 geared trucks fare better in the mileage arena and can often see better than 20 MPG with tuning. However, if all he's looking for is fuel economy and he's already at 19.5 MPG now, I doubt there would be a significant enough gain to offset the cost of getting a programmer.
There may be more gains if he does a lot of city driving or mixed driving. If he's got an average number for his day to day, we'll be able to better advise a solution.
Take care.
__________________
Bill Cohron - The Mad Doctor  
Power Hungry Performance - The ORIGINAL in Ford performance tuning... Since 1996!
(678) 890-1110
www.gopowerhungry.com - Home of the Hydra Chip, Minotaur Tuning Software, and the new Orion Reflash System for Navistar!
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