We tried reusing the existing wiring and found the injectors we wired up correctly except one were the wiring colours reversed.
You lose VCT from the rb25det as the rb20 doesnt have it
The ECU fried when we tried using the rb20 ignitor box
Just whilst the engines out, change the loom straight to the Rb25det loom, injector loom, coil loom, ecu and ignitor box
youll need to figure out how to wire up the body harness and get the wipers, speedo, fuel pump etc all working.
Another issue i had was the injectors had seized from the engine sitting so long, had to hit them with 12v so they free'd up.