Power Tuner for Gas engines

I had the hypertech max energy on my 5.3 liter chevy and it did make some difference. I had a 1/2 ton pulling a superlite 24'FW and I noticed about a MPG improvement in fuel mileage and it did shift firmer. I saw no difference in the ability to climb grades. Now running solo it seemed to have a lot more throttle response and more low end grunt which erased any chance of fuel mileage gains as I could not keep my foot out of the skinny pedal (probable all in my head). Don't expect any earth shattering results on a gas engine. As far as warranty goes I know most dealers frown heavily on them. That being said I experienced a number of factory recalls on my 6.0 PSD that was programed from its first tow and my local dealer never hesitated doing the work but would always tell me that they could see when the program was installed and uninstalled.