First of let me say if this has been covered I apologize, I didn't see it anywhere. I am curious to see where the best cruising RPM is for maximum fuel economy and any other tips you guys could suggest. The truck in question is a 2000 F250 CCSB 4x4. Automatic with 3.73's. I have not checked the fuel mileage since I have put the current mods on it. But when the truck was stock it was getting right at 16 with highway rpms right at 2100. The truck now has a edge evolution cts tuner, napa 6637 filter, 5 in. mbrp straight pipe from the turbo back. Do I need to slow down while cruising on the highway to help my fuel economy or is the pretty respectable. It is on 305/70/16s. I know this does not help but am looking for stock rims and tires. Any help is greatly appreciate and sorry for the novel just now.