At work we have a few 2004 f250 diesels. The bos got superchips tuners for them. The will do tow-safe, economy, and power.
The power setting does 'feel' stronger, and changes the shift points.. lowers fuel economy alot.. The tow safe 'seems' to do nothing except lower fuel milage. Economy also LOWERS fuel milage.. go figure.. I've had to switch all the trucks back to factory tuneing.. and that IMPROVED fuel economy over any of the superchips programming...
Oh well.. at least the superchips units can be used as code scanners...
Soundguy