OK, here's an obscure one.

Most aftermarket catalytic converter suppliers (that I've researched, I guess) say that you should perform proper burn-in on a catalytic converter (i.e. expansion procedure for the vermiculite encapsulation mat) when installing it - something along the lines of "start engine, let it idle, rev it at 2000-2500rpm for 2-3-4-5minutes, shut off, let it cool down completely" (i.e. effectively leave it overnight). Some suppliers say that theirs are "pre-burnt/expanded". A decent amount are silent on the topic.

I've not seen anything about this in Toyota's official literature.

Anybody got some insight? I assume Toyota's are pre-expanded to avoid a potentially very costly failure, but I'd love to see some concrete examples.