Sports cat mk2 vrs

Hi all, been looking at getting my car mapped in the near future so plan on getting an uprated fuel pump, exhaust, intake etc etc, however has anyone here got a sports cat on theres and is it worth it ? Lot of people been saying just get a decat but frankly I'd rather just save and spend a bit extra for reduced hassle of having to switch it out every year and potential (Although unlikely) legal trouble. My only reservations being I've heard they can potentially still fail your MOT for emissions and potentially be a waste. Any advice would be helpful, cheers!