I have a 97 impreza obs i'm also attempting to do the same with. I love the idea and so many people have done it already idk why no one has commented. I was told you'll need to get the wrx and obs harness merged by someone, get the wrx fuel pump, turbo cross member so it'll have the notch for the up pipe, then its pretty simple after that. oh and grab the wrx ecu of course. Now this may change slightly if you plan to upgrade the wrx engine to bigger turbo, injectors... tmic, fmic, stand alone are all good choices at that point. good luck and if you get any more info on the swap lmk cause i'm partially clueless as well. I know a little from what i've been told but haven't been given a complete list.