The engine is all stock only real upgrade would be the 4" turbo back exhaust (since I had to replace the exhaust for the conversion anyway). The injection pump was tuned for fuel efficiency when I had it rebuilt. I built this truck for longevity and fuel economy not as a toy. Something to last forever and be easy to work on. This is a first gen Cummins with a non waste gated Hoslet turbo and intercooler, Bosch VE pump, mechanical injectors and a hydraulic transmission so there are no electric sensors to fail. I also installed a Derale 14210 extended cooling transmission pan and an in line transmission cooler to keep the transmission cool which was the weak link in the original Dodge Cummins set up. If you do routine maintenance and don't abuse this truck is will last a very long time. The old Cummins are not speed demons but with the 3.55 gears and the 4 wheel low you could pull a house off of its foundation.