Where are you located mate?
Ive got a pretty clean V4 STi sitting in my shed that I hardly drive, been thinking on and off about selling it. One of those situations where I'm unsure if its worth keeping for the classic in the long run, but hate seeing it not being used!
I put a GFB respons in my V4 STi, only because the factory one broke due to age and brittle plastic. Have it running 50% atmo 50% recirc and the car runs fine. Benefit of the respons is you can recirc or vent to atmo 100%, or anywhere in between, in 2 seconds if you want.