Wow...
Thats amazing about your full size truck! You really should tell Chevy, Ford, GM, Toyota, and Nissan, and all other makers of full size trucks about your record breaking mpg's...25 on average 90% loaded...was it the truck that was loaded or you?
I've never heard of a full size getting more than 20 average, while fully loaded, with no mods, as you say.
I'm sure the engineering dept's of those companies would be more than happy to hear how you were able to accomplish this feat...downhill w/ a tailwind, and no brakes? 90% loaded with air? what's the secret? inquiring minds wanna know!