Its was a learning experience with me aswell. How I thought of it was if I was using the au harness and sensors, throttle body etc the
ecu would still think it is running the au motor so would not need to be tuned. As for the coils the ba and au motor run the same trigger wheel so nothing was changed there, if that makes sence... Therefore the dash wil not have to be changed. I did howeva have to put the vernier gears in to hold the cams in time... Mine was the vct motor but totally different setup. As for the turbo, being a s2 it will cut at any sign of boost so will have to be tuned to suit.. 2bar tmap injectors etc.. Hope this helps.