With a set of 4.10's, 33x12.50 MTR's, Tornado, Superchip, 700R4 conv., 2.5" SL, 3" BL, K&N Conical Filter, Oil additives, and a lead foot I'm averaging 15 mpg. I drive 400-600+ miles per week and check it often. I know that the ODO is off but only about 5%. With my setup at 65 mph my tach is at...