He had a programmer on it. I heard MANY lift 7.3 get that good of milage of course u gotta drive easy on the skinny pedal. Now stock. Never heard of anyone using a programer. Who knows it might get 20-22
7.3 is one of the best diesel motors made. That's y u can't hardly find em. If u do and the owner knows what he has they think its a gold mine when they price it. Try to find a 7.3 excursion with 100-150k miles and see how much they still sell for if u can find one for sale.
the excursions are even harder to find. i know 7.3s are the best diesels out there and i'll have one someday.
i like diesels in this order 1- 7.3 powerstroke 2- cummins 3- 6.0 powerstroke 4- 6.4 powerstroke 5- durasux (if i cant get anything else) and my buddy has the 6.0 with 37's and gets 15mpg with the sixgun on 4