[924CarreraGTP]

AHHH... Witchhunter for a car that he says runs great? Really? What does Witchhunter do besides run some solvent through the injectors and test them. I guess they rebuild them if they're broke right? You can run B12 chemtool in your fuel and it will break up carbon, varnish, and even in some cases melt rubber. I don't see the need for removing the injectors when you can run solvent through the fuel to perform much of the same effect. Plus if you don't clean your fuel tank, it doesn't really matter anyway because you're going to dump more trash into your injectors.
This goes to show you that too many people on here have too much money to fix s*** that isn't broke. I have too many Porsches to do that.
As for super charging, many will tell you to just upgrade to an S4, but I like the styling of the early 928 much more and pre 85 U.S. cars are non interference engines. So at least you wouldn't have to think about destroying your engine with something as simple as a timing belt on an '83. If I was going to super charge a 928 it would be a 4.7 liter. However, as others have said this isn't cost effective, but neither is 928 ownership in general. Build the car that you want, not what others tell you that you should build for cost effective power output. It makes a hell of a lot more sense than sending your injectors that aren't broke to be "fixed".