You are spot on !I was chatting to a family member who is an mot tester aboutthis and he too suggested the fail was simply for removing them. This surprises me that its not detectable through the emissions as i didnt think the downpipe cats were particularly visible, meaning if you didnt mention the removal of them then they wouldnt be able to tell.
Not now as they are stipulating a missing cat is reason for rejection and on its own merit a failable item (missing cat).in the real world the only reason the car would fail due to the removal of the cats would be emissions
Just for removing the cats. It will still pass on emissions,most testers dont know that cats are supposed to be there though,you just tell them the only ones are in the down pipes.