AF:
I am not a fan of superchargers on small displacement four cylinders, unless it's a centrifigual blower (which have more common power delivery characteristics of a turbocharger, they don't spool till ~100,000RPM).

You can only force so much air into a small displacement four cylinder, turbochargers seem to induct air much more efficiently and make a lot more power.
^what he said, and...

A turbo is more efficient than a supercharger in that a supercharger is only as strong as the engine that powers it ( supercharger runs just like your alternator or ac pump, a belt run off of the crank spins a compressor--turbo uses the exhaust gases of the engine that are already there, you're just putting a compressor wheel in line of the exhaust, using 'free' power; a supercharger uses the hp off the crank, initially removing hp, but returning it more so in the form of boost )
Superchargers tend to respond better to larger displacement engines rather than a 4 cylinder...v8's, big v6 and the like...