Classic wrx 1993

Hi I am sitting a v1 with an empty engine bay and have finally sorced the correct near as original closed deck I can find. I was running straight exhaust fmi and air intake with maf on a polar chip ecu. What I would like to find out is on a standard ecu what exhaust would I need and could I run fmi. Going back to original air intake. I'd like to keep it to it's factory Limits ? Please lend a hand it's been sat empty for 6 weeks looking sad lol.