My everyday driver is an '04 F-150 with the 5.4 liter V8. It's a great truck, but as you can imagine it's pretty thirsty -- 14 city, 15.5 highway is the best I have ever gotten on it. When we started carrying the Hypertech Max Energy Power Programmer I decided I would try one. I figured the gas savings over time would pay for it and I'd get a performance increase to boot.
The first thing I did when I got it was plug it into my laptop and update it to their latest tune via their website. Install was easy; I just followed the instructions. I bumped all shift points up about 300 rpm to squeeze a bit more out of it and besides that pretty much left it alone. After telling it to upload, the install took about 5 minutes. REAL easy to do.
The true test is my annual trip to Ohio from home base in Indiana. It's about a 400-mile round trip. I was really anxious to see what it did for my gas mileage. Last year without it I got 15.5 mpg; this year, just under 18. Not bad, given that the engine is so big. The increase was just what their website says it would be. I bet with a new air filter I would have done even better. City mileage hasn't really changed, but I attribute that to me getting into it more because of the different shift points!
Overall the truck idles better and is having no problems with it. It's a recommended product!