im pretty sure the attessa is stand alone as well and doesnt need the stock ecu. leewahs car had autronic and no issues with attessa (that i know of). also seen GTS4s using normal R33 GTST powerfcs which arent "designed" for an attessa system and it works fine. On the cars loom there will be wire splicing by factory for things like TPS, RPM, SPEED etc in the wiring so the ecu won't know its there. The ALSD on the GTST is the same, it just copies the TPS wires (and others presumably)