Ok i fitted a Cats2u (cheaper version) back in 2019, always get the odd P0420 rear eml on long runs ( post cat sensor code) but otherwise all seems ok and has passed mot twice, however at the trackday last week i noticed a rattle noise from exhaust which i presumed was one either rear original silencer or one fo few remaining heatshields maybe....but just had car up on ramps and its the cat insides that are rattling around inside the can :( , will have to see what ive got in loft think there is 2 stock cats which are serviceable or maybe graft into cats2u pipework, or buy another cats2u jobby hmmm
OK got cat removed today, as you can see its had better days :D
First video is just after removing it.
Second video cut it open to investigate :D
Ive refitted stock orignal cat for now as just a temp measure until i get around to sorting the turbo setup later this year.
Sorry to hear.
For the aftermarket cats I like the spun metal versions where the body is manufactured around the catalytic converter so this kind of thing doesn't happen.