V5/6 Non vs sti
Both non and sti had 440cc yellows and afm. Only real change was the ecu for sti to match the more aggresive cams, lower c/r and a higher boost limit.
V4 vs v5/6 sti
Coil pack with inbuilt ignitor, offset intake mani bolt pattern, intake mani less balanced on v5/6, idle stepper on tb, thrust setup, phase 1 vs 2 injectors, afm, smaller turbo on v5/6, speedo sensor, heads, bakelite cam wheels on the latter, 8 bolt bellhousing, different pistons same material I think, alternator, bov setup, different make of ecu, water temp and boost solenoid I think.
Not sure if all V4 had obd2 and test connectors mine does.