I've done turbo removal & repair with standard hand tools. Injector removal and installation did cost me a torque wrench that reads in in/lbs. but that was a $30 Harbor Freight purchase. Other than that, you can work on a PSD with your average shade tree mechanics set that most all of us have.
Flare nut wrenches are handy, a set of crows foot's can be useful as well as an assortment of Torx drivers but none are a must have.