Is there anything you'd want to change about your Cummins engine? Do you want to go further and quicker, or does it require some maintenance? Fortunately, there is an entire market for 1998.5-2002 24V Cummins performance upgrades.
Generally speaking, factory-built engines provide superior fuel efficiency. Manufacturers don't care much about metrics like top speed or torque. The average person does not consider this at all. However, many diesel drivers desire these 5.9 Cummings 24-valve performance upgrades for their vehicle.
You may customize your vehicle using diesel aftermarket components to suit your needs better. Check over this list and see if there are any noteworthy additions or improvements.