I do have to be skeptical when anyone claims 26 mpg in a F-150. I suppose it's possible, and if you do get that, consider yourself very lucky. The best I've seen in mine is 23.2 on one tank of gas - and I have a comparatively light truck with a V-6 and manual trans.

 

I've been running Troyer Fans for about two months now, and I have to say no noticeable mileage increase. The idle also dropped, which seems counterintuitive, because you would up the tune to handle the load of the OEM Fan.

A new tune may be in order. I'm thinking that any change to original parameters requires a computer tweak.