In testing we find that the catalytic canisters fitted inside the original exhausts now fitted to brand new 2-stroke mopeds are effectively useless for cleaning up emissions and deteriorate very quickly in a 2-stroke engine (do not cope with 2-stroke oil).
Emissions are not tested at MOT in any case and the only exhaust with a cat for your bike is the original genuine one (very expensive and low performance) so for these reasons there are very few people who choose this option when the time comes to replace it.