have fitted panel filter and full decat on an STIV. Do i need a remap? any ideas?

 

Sensibly, an sti5 should have a remap before anything is fitted at all - the fuel here simply isn't good enough.
If you don't want to go that route unless absolutely necessary, definitely use an SUL with octane booster, and fit a KnockLink, preferably also an AFR meter as well; then you can keep an eye on any trouble

 

the car had a p1 ecu fitted on arrival to uk when the car was in standard spec. Does this mean i shouldnt have any probs?

 

Even when you decat a P1, a remap is regarded as a wise move

 

A P1 ECU, AFAIK, is an sti5 one but will retard more happily, ie is safer on UK fuel. But not enough! Fed with SUL + booster I suspect you wouldn't have any problems, but a remap is always best, and a knock meter a must, really.