to directly answer your question, you cannot simply "tune" our cars to get significant gains. some members have gone with standalone engine management systems, such as the "megasquirt 'n spark", and they have seen some minor gains. Alex on here put a MSnS on his KLZE, and he got a little bit, but he also has a jdm motor and several bolt ons to take advantage of a new fuel/timing structure. start with bolt ons, and then tune from there.