Ford Australia has switched off the rear O2 sensors as a minimum because the cars here come with headers not cast iron manifolds - however most the good tuners (Diablo, SCT etc) allow you to do that anyway. I know one guy in the local club bought a chip, larger exhaust and cold aor intake and reports 400hp at the crank....
I dynod my car at a local club day about a year ago and it was 217ish at the wheels.