Having a 2000 F-250 with the 7.3, since new, I have the following things that I did and am really happy with.
-4" exhaust from Dynomax
-88mm ATS Ball Bearing turbo
-A pillar gages including turbo boost, Pyro and tranny temp
-Chip from DP Tuner. I run it always in the 80 hp economy setting
-Mag-Hytec differential cover
-I had a race shop build my transmission in Reno, NV (Trans-Craft, but if I was in the south I would get mine from Brians Truck Shop
- I upgraded my alternator to the large case 160 amp.
Beyond that I am still happy with the truck and know it is a durable & dependable truck.