I know just enough about diesels to get myself in serious and expensive trouble if i was to try and work on them...Now as for resetting the computer engine management controls..i can tell you a good "Tech" on gas motors that knows his way around the ECM and TCM computers can tailor the program in any vehcile to how it is driven for the most part and increase mile, increase performance within a certain settings, towing or high performance any number of ways...so i would have to believe that the same can be done with a diesel...it would all depend on how good the person making the changes really is....
Let us know how you make out and where the changes made a difference...did you lose power on accel, did you lose torque at other areas of the power band, were there any other improvements other then an increase in mileage, were there any changes that were determintal??? Let us know...