When I traded my '02 dodge 3500 diesel I pulled the Edge performance chip. Haven't really tried to sell it yet, but if you would like to buy it (or know someone who would) I'm open to offers (new $500). Used it a year and boosted fuel efficiency by 25%. Since most of my driving involves pulling an enclosed trailer, I can't tell you what kind of gains to expect on the highway. performance gain is impressive!
Oh, it doesn't fit on my current truck.