I’m looking to buy a UTEC but am a bit unclear on which software version I need to run for my swap project. I run an 05’ WRX motor, engine sensors, and engine wiring harness BUT am using an 02’ ECU, bulkhead wiring harness, and fuel pump controller. My question is what actually requires the open-loop fuelling (v4.2) and would I have to use it? I imagine this is a feature of the 04-05 stock ECU and therefore I don’t need it, but just wanted to double check.

All comments appreciated…
:D

Just run the latest firmware. Unless you have an automatic, there is no reason not to.