Having a stab in the dark here but would your want for a FMIC have anything to do with a vortex?

Assuming the loom you have is from the same car as the engine, you can only use a V5 or V6 ECU. I *think* you can use a V5 or V6 STI ECU but will need to re-pin a pair of wires to make it work, same way as they do to use a power fc in same vehicles...