Well, I have to say I agree with some of the previous comments regarding "drive a 6psi boosted 914" before you draw any conclusions. It really is a decent power package that transforms the stock 914 quite nicely. Configure to what you have, rather than trying to force more out of it then can be had, IMO. If you think you want more than that kind of performance, then you must be prepared to take it to an entirely different level. That level however, I'm not convinced is a very resonable vision given the foundation from which you will have to work from. If you just have to have more power, then perhaps a modern turbo four, six or V8 is in your future.
I learned about turbo's the hard way. Very little printed matter was available in the late '60's on turbochaging, so we (I) though hard about what we were trying to accomplish. I was fortunate enough to befriend an engineer at Air Research who perhaps took pitty on a young guy with dreams. We designed nearly everything, and did a lot of fabrication and adaption. The wrong decisions were quickly evident, broke some stuff, but learned a hell of a lot. I know all that stuff was old school compared to what has evolved since, and what is available today. (And) I do not profess to be current any most of it, especially the electronic controls. The fundaments however, haven't changed.
Andy