Hi all. I've got a 2003 F-250 4X4 6.0 with a K&N on the in-side and 4" Banks exhaust... no chip. The truck had about 85K miles when I purchased it a couple years ago (original owner added filter and exhaust mods), and currently has 130K miles. For the weight, this truck had a pretty good kick. However, somewhere along the way my mileage dropped from 19 mpg to 16 mpg, the pep it had seems reduced, and, interesting enough, I'm not hearing the turbo whine at the same level as I use to. Ford dealer mechanic says his tester shows everything working as it should, but thinks the "problem" could be some change Ford may have made in the programming... and, of course, the "latest and greatest" gets downloaded each time Ford services the truck. Losing the kick doesn't bother me nearly as much as losing the mileage, and I can't say exactly when the change occurred, but seems the two are likely related, along with the possible loss of boost. Any of you diesel wizards have any thoughts on this? Any help appreciated. I don't know enough to even guess. -mac-