I don't know if a few of us have gotten magic trucks or what, or if the stars were aligned, because I've gotten a best of 25MPG. On seperate occasions I have gotten 24.3 and 23.7MPG.. with stock tires and just a K&N filter, straight piped exhaust. This is running under 2k RPM's on the freeway (speed limits on that trip were 90 - 100 km/h).
Average I get about 19, half highway half town, I live in a rural area, have a light truck (reg. cab) and a handshaker so I guess that helps it be a bit more efficient too.. Even with big tires on, calculating for tire size I can get 22 when I try.