I wish captianjohn2008 would have said what he did to make his truck get that better mileage.
From what I know about these engines I would have to say he "Spartan-ised it. Is my guess correct Capt? And yes, it will help with fuel mileage that much!
I'm not a big fan of tuners when towing or trying to make things reliable but if I owned this engine I would definitely get a Spartan tuner. It's one of the few engines that make SUBSTAINTIAL fuel savings if you do a tune and delete the DPF. It will also make this engine a lot more reliable by getting rid of the BIG oil dilution problems this engine has. Depending on how many miles are on the stock rockers they already may be toast?
OP, this engine is very maintenance intensive. I mean big, big, big. You better get to know the maintenance schedule very well and stick to it or you're going to be sitting along side of a road somewhere.