it really depends on the application, chevy gas burner against ford gas burner-chevy wins, deisel on the other hand is kinda iffy. the powerstroke is a beast of a motor and ive heard that duramax isnt exactly a badass motor unless its backed by a allison transmission then its kickin everythings ass except a dodge cummins lol, also it depends on the year of both trucks, if the ford is newer and hes put a tuner and pipes it could be messin with the computers default settings, not everything is programmer safe, some things are not meant to be screwed with...