if your in a RS and using the stock Chassis harness then no its not plug and play and wiring is involved. If you are in a 2002-2003 WRX with the stock chassis harness and the stock ej207 engine harness it is as we described plug and play. There are 2 harnesses at work here chassis and engine. as far as ECU you can plug in a v7, v8, usdm wrx, and have them all work. the usdm wrx will not run avcs, either jdm ecu will.