since the rb20 is (i think) 8bit, i would recommend an emulator (moates or others - haven't kept up) + tuner pro RT. This should allow you real time tuning for a small (compared to other mods) price. It should be as easy as putting a socket/ziff socket on your ECU and the buying the emulator + paying for the real time Tuner pro software (its only like 30 bucks - but then again I am a software engineer, so I don't mind for paying for good software like beyond compare), and start it up all on your laptop. You could also just socket the ECU, buy a burner and use the free TunerPro version (or other software packages), and just reburn the chip as you go.
Either way, its a lot of fun
