im averaging mostly 13.5-14.5 babying it! stock 4x4 auto reg cab XL it doesnt seem to get much better on the highway if any at all and i do not let it idle very much at all.. im not sure if this is normal but cruising my truck seems to be sitting at 8-12psi of boost depending if i am driving on level roads or if i have a slight grade. any kind of bigger hills it jumps up to around 20psi..... 28psi WOT. i thought cruising id get less than 5psi but i am not sure if maybe i have other issues.....
09 F250 XL Plus Reg 4x4, SCT LW w/Erics tunes, S&B, Full SS Flo-Pro 4''.- Sold
18 is fine if it is a cc4x4, with all that power. My 7.3, manual tranny gets about 19 on the highway.
2002 f-350 PSD, 4x4, cc short bed, 6spd, ccv mod, airdog, AIS filter, isspro ev and scangauges, detroit TT, ITP boost annihalator, ITP RR, bellowed up-pipes, ats housing, turbomaster, 3.5 dp magnaflow, very happy with ultra smooth and linear PHP 50t, 80DD and "whisper" tunes.