I thought I relied to this, but i guess it didnt show up? Oh well.
What exactly are you looking for, exhaust, turbo upgrade......
You can buy and install the parts in the Banks kit from different vedors (not banks parts, but the same items like downpipes and such) for a fraction of the cost of a Banks kit, and last I knew Banks 1st gen cummins items were long gone. Unless someone has some old stock.
Better yet, what kind of power are you looking for?