Flyin' Ryan SCT customers report ~17 mpg in a 2wd Dakota 5.9 with his 'stock engine tune'. Plus about 35ft lbs of torque increase across the RPM band (the power increase is dyno proven on a few different trucks). You could consider a re-program but don't expect the same exact mileage. 4x4 vs 2wd and the 1500 is probably 1000-1500 lbs heavier.
The other thing you can do is a tune up to ensure everything is healthy. Check your plenum gasket, replace your plugs, wires, cap and rotor.
Do you have a link to these guys?
How much will it cost me to get 4 mpg better mileage and 35ft lbs torque? The 5.9 will be going into a hot rod, probably 1,000 lbs lighter then a last gen Dakota. Gene
