for an EG??
I know on EF's the si and dx harness's are completely different. I would guess no. really I highly doubt you even have to replace it. just make the si harness work, by lengthning, or whatever the exsisting wiring. there's really not that many connectors and the ecu could really give a shit about the majority of stuff (interchanging sensors and shit)
prime example is the mpfi swap.