I was going to suggest HJS cats, with the euro being down they are very reasonable at just under £300 a piece. And I bet they are better made than the stock ones. Plus they are ECE approved.
They will pass the MOT no problem, but they will cause you annoyance by occasionally setting off a post-cat lambda error and sometimes CEL.
There is a easy fix, just some spark plug anti foulers fitted between the post lambda and the exhaust pipe to lift the sensor out of the pipe, but its a bit ghetto and non-stock if you care about that sort of thing.
I think these are the ones I bought.
https://www.turboperformance-shop.de...s-bis-2600-ccm