[KobaltBlau]

Lots of people turbo vw-ish flat fours for drag cars, sandrails, etc. So it certainly can be done. I think the higher output motors tend to have few VW (or porsche) parts, mostly aftermarket parts.

I don't know very much at all about what a stock 912 motor is like, but in general you can run low boost with a stock motor in good condition with non-super-high compression, but you need to start upgrading internals if you want to go to higher boost numbers.