Tuning ,ECU's and NCT Emmissions.

I have a post up at the minute about fitting an exhaust before I tune car. My question now is this, is my standard ECU remappable?
If so will it pass current Emmissions in ROI. Along with exhaust I want to fit K&N Panel Filter. Car again is 2000 Impreza Sportwagon UK Spec. Has anyone remapped standard ECU?

Ecu is remappable but the car wont pass nct emissions with the full decat. Will have to swap back to standard exhaust for nct

^^^ what he said, you could consider a catback exhaust. it'll sounds good and flow better but will still pass nct.
the panel filter wont effect emissions of course.