928 GT + Supercharger

Hi Everyone.
I need some help/advice:
I can get my hands on a 1990 GT that's in superb condition. I am a bit of a purist, so I was mortified when they opened the hood and there was a supercharger attached to the engine.
Having done a bit of research I see that it's a fairly common addition to the 928 range. Question is, is it still a good buy if I am buying for investment and will the car appreciate in value given that the engine, technically, is not stock anymore.
Appreciate any comments/suggestions. Thanks

A supercharger isn't that common of an aftermarket addition to a Porsche 928. I would guess that having a non-stock engine would limit the desirability for an investment. If the installation was done well, the supercharger can be removed and the engine returned to stock configuration.