Originally Posted by
Reuben
The 20K conversion does not require a patch harness for the GTB at least, The STi ECU literally plugs right in (bar the wasted spark wiring), so do mentioned that... Phase two requires much modification. But you're right, can tune it. But then why wouldn't you get a ver. 3/4 daughter board, and get even easier tunability than a phase-11 ECU, if tuning is a thing he wants to do?
I can see the attraction to phase-II though, obd-II is beneficial there for passing emissions right? Not something we do down here...