Bill tweaked the program in our 2005 5.4L Expedition. At the moment, we're averaging 20.1 mpg hwy. Of course, we have a 3.30:1 gear ratio, which helps a bit, but it's still more than three miles per gallon over stock with highway driving. Woo hoo! We'll have to keep driving it around town and see what the numbers look like. I'll keep you up to date.

 

my wife is looking a low mileage '05 expy right now, it looks like we might be getting some tunes, 20mpg is pretty good in a land barge

 

...but you gotta love all the room!

Give us a call if you have any questions!

 

would 3.73 gears help or hinder fuel mileage? of course a 3.5 inch AFI intake, valve body in the trans, underdrive pulleys, e-fans and possibly 39# injectors eventually

 

Depends on your current gear ratio. The 3.73 is a factory ratio for the towing option. It causes your engine to rev higher at 75 mph than say a 3.30:1 ratio. As such, if everything else is equal (same tires, same engine, same vehicle weight, same air drag, etc. etc.), you'll burn more gas using it than you would with the lower gear ratio. But, you'll have more power in a high demand situation such as pulling a trailer out of a dead stop, up a hill, or when you're drag racing.

Which of these performance factors is more important to you? 1/4 mile times or high mpg? You really can't have both.

I meant to add: That's great news, Corey! I'm hoping Bill can work some of that magic on the economy tune he's doing for me!

- Jack