I haven't seen the manual, but I do know that Saab's first use of water injection was on the C900 Enduro which is one thing that makes it a milestone vehicle. My turbo car has a H-block engine so I'm not sure from a turbo perspective what differences if any that brings, but I'll wait till the car is here and registered again before getting into plans for upgrades other than knowing that one of the first things I want to do is put a stainless exhaust system in such as the one made by Ferrita.
Beyond that, it's hard to say. So many choices. It'll depend too on the internal condition of the turbo. Other than it's wastegate issue, nothing else has been evident so far. 8-)
Craig.