Yeah, Catloc sell them directly to Toyota and Mercedes, and I’m sure now somebody mentioned it we did do some for a Honda jazz recently.Catloc is the one approved by Toyota. If you get a stolen cat replaced they include it now. Tamper proof bolts, security marking etc. I see it mainly a deterrent similar to the steering wheel or gearlever type locks used to irritate the TWOCers in the 90s. Security marking isn't worth anything if the Police don't try and catch them.
I've seen other third party ones that weld extra metal bars to the edges of the plates and use steel cables around the cat to further increase the nuisance factor. More likely to be a nuisance to the owner that has to replace the exhaust!
The Catloc ones we do are generally 2mm stainless for the main body and 4mm stainless brackets. They use coach bolts to affix the so that you can’t get a spanner on to just easily unbolt it. The Toyota ones are pretty big.
I’m sure I can recall one lad saying when they get the designs approved at Catloc, and have a set amount of time it has to hold up to somebody trying to remove it.