I also put in cetane booster and don't drive over 65 mph. That's the only way I can hit over 18 mpg.

tractornate, I've hit a max of about 38 psi for boost while empty. I didn't get over 30 psi for the first 2000 miles then it just shot up.

[QUOTE=bigblock_drock]18.5!! and u ppl are complaining about the MPG ive never seen a 6.0 do that good! :-D[/QUOTE

Ive never seen over 15 highway empty with a hurrican tall wide downhill.

90 percent of all the MPG post are all in the 11 to 13 range that ive seen.