I also have done a lot of traveling with my '01 F350 CC dually, and I never see anything over 15.5, hand calculated. I have tried different speeds on the hiway empty and just pulling my gooseneck empty. Avg. around 12.5. I have edge juice with attitude, edge evolution, Hi Tech turbo, AFE Stage II, 5" exhaust. If putting new orings on the injectors will let me see 20-21 empty then I am all over that.