Here's what i have a 90 si (EF) what i want to put in- b18a- b18a wiring on motor- PR4 ECU- 90 axles- custom linkage- avid mounts. I keep reading that the swap is basic but i started doing it and i think im missing a part of the wiring. the key thing i think im missing is the harness from under the dash. do i need this? if not how exactly does it wire up because i think i got all the mechanics i jus need the electronics. please help me. thanks.