I have a 95 f250 with a DIY 6637 intake with an AFE big boost filter on it, diamond eye 3" dp to 5" straight pipe, run all synthetic fluids and mix a little two stroke oil in with my fuel. I get about 24 mpg on the hwy doing around 60 mph. 5 sp, 3.55 rear, and stock tire size. The truck got 21 mpg hwy before the mods. Keep her under 2000 rpm, if i run any higher than that my mileage goes to ****.