Hard to say...I'm still in cool temps and Winter gas but believe mine may be a little better at high speeds...it was never terrible at slower speeds before, 22-23 mpg if you keep it 60-65 mpg on flat roads.
I am still having trouble with a feeling of a lack of power mid range. The RPM's will sometimes "stall" at a certain point and even drop down during acceleration. Feels like it downshifts but it doesn't its weird, the RPM's just drop by like 300-400 at certain points.
Truck was great for a few days after the plug change...then seemed to go bad again. Maybe try putting the '13 plugs in?
2011 F150 Ecoboost Crew Cab FX4, black, 6.5 ft box, max tow, Luxury Package, Bilstein 5100's, Duratracs, SSi custom tuned, aFe intercooler, 170 thermostat