s/c GS-R... go with high RPM's and vtec.

I'll continue to advocate superchargers for low-boosting engines, simply because you wont have to deal with turbo lag. I find that, among equally boosted turbo/supercharged cars, I have more fun in a supercharged car since boost is available immediatley. Feels like there's a bigger engine under the hood, rather than a boosted little one.

However, if you're going "fast as possible"... use a turbo... you'll find more adaptability in the long run.

Just remember to be careful, and spend an hour of tuning for every hour installing.