A v-8....... lol Ya thats the 3 best besides displacement and fine fine fine tuning.
No one invited you V8 people here. Go away!
The only supercharger options are an overly complicated M112 set-up and a Procharger. Neither of which are very practical.
You best bet is a single turbo set up. You can run twins but, it is really not much of an improvement over a well built single set up. TMA Turbo is supposed to be making kits soon. They start at around $3,500. That is only for the the turbo kit itself. You still need to beef up the drivetrain, fuel system, possibly upgrade the internals (depending on your boost level and horsepower goals), and get it tuned.