I've noticed an increase in mpg of about 2-3% in the Mileage XS Saver programming with my truck which translates to about 20 miles per tank more than the stock program. I will say that the 87 Octane program has noticeable changes over the stock program. My truck has the 5.4L with the 3.73 rear end. I am running a K&N cold-air intake with an Airaid PowerAid throttle body spacer. In the Performance program I have trouble keeping my foot out of the accelerator because of the increases!
Great easy upgrade for mpg or power boost
I really like this thing. I've never used any kind of programmer before. It was easy to install an put a noticeable amount of umf into my 4.2L V6. Changing shift points and press is nice as well. I have it set to the performance tune right now and have seen significant increases in power and acceleration with the mpg remaining the same. On the 87 octane setting I saw slight power increase with 1-2 mpg increase. I have yet to tune it to the fuel saver mode due to it being too much fun