I have had Jesse's tune for about a year now. I had him make the usual changes to shift points, firmness etc... and tune for a 180* thermostat. I have the stock fan, non electric on an 02 suburban with the 5.3.

Got the tuned pcm, put it in, I could feel a difference and was happy with the mileage improvment. I only let the Suburban get to a half tank because it makes fill-ups a little easier on the wallet (at least it makes me feel better about them) and always reset my trip meter.
I consistently got about 200 miles out of that half tank before the tune, and after the tune I got about 210-215 per half tank, so there was an improvement. A few months ago I finally realized that I never installed the 180 thermostat that he tuned for.
Dug out the thermostat and put it on the truck, filled up the next day and by the time I reached the half tank mark, I had 255 miles on it! Thought it might be a fluke, so I waited awhile (and 8-10 fill-ups) before posting anything.....but its the same. My driving is mostly city, nothing else changed but the thermostat. I wish I had put that damn thing in a year ago when I first got the tune. Some of you might wonder what my actual mileage is, and I dont know....I have never checked it, I always go by the trip-meter.

Sorry for the long post, but I wanted to say thanks to Jesse and let you guys know my experience. Ron

 

That is a good improvement. From what I have read most people experience the opposite.

 

consider the cooler weather were getting this time of the year. my truck has always gotten better milage in the cold.

 

Thats true about the weather, but hot or cold I always got 200 miles out of that half tank....I guess the 200 is about what everyone is getting?

 

The cold helps me. I normally average about 300 miles per tank*26 gallon* and just recently I made it up to the 395 mark although a bit more highway had to do with that. Right now with the cooler weather i'm seeing about 330-350 per tank.