Darkhorse, I think your going to have to ask the diesel guys as it appears you have a 2000 PSD. I dont really know as much about the diesels so I'm going to take a guess that the lower horsepower daily driver tunes will get you the best mileage, but like I said, I dont really know for sure. I think any performance tune should do well because they are designed to make the most of each shot of fuel. Just dont forget a tow tune so you get the best mileage while towing.
