I contacted lambda tuning and they told me that they have tuned many 02 Impreza rs2.5 ecu’s with their tuner. I’m currently going to save up to buy the Bluetooth tuner and the tuning license. I think the total including a custom map will be roughly 600-700 bucks. I’ll get back to you guys after I buy them and install the tune.I have an 02 Impreza (NA ecu like yours). Check out project lambda tuning, it allows you to reflash your stock ecu. You can play with all the maps yourself or have Mike tune it for you. He did a great job with my swap and is a great guy, he’s really easy to work with.