It really all depends on how many $$$ you can spend and what your goals and constraints are. People have gotten great results by adding blowers (Whipples, Prochargers, or even small roots) to otherwise stock motors and limiting boost to just a few lbs to keep it safe. If you have more money to spend, you could do a full teardown, upgrade some internal parts, drop compression, and add a blower system with higher boost to make more power. Or, if you want to stay naturally aspirated, you could build something bigger and make power with better cam/heads/compression. Of course a key element to any method will be the exhaust system, so that's always a good place to start.
-brian