Mate - I put one on a v6 petrol, but not a diesel. It definitely gave the vehicle more punch, which was great in sand and around town. It didn't do anything for the fuel economy that I noticed.
Sorry it is not diesel info, but that may come later. I am considering putting on in a 75 series troopy to give it a little more punch (if it works the same as it did on my petrol).
Cheers.
Ed.