Sorry to hear about your accident, but glad you ok and can see the bright side.

Good points about the CATs, many years ago removed my main cat and it passed emissions ok as it had 2 other pre-cats in manifold, but rules changed few years ago, about physical presence so I put it back on.

Also, on the engine cover advisory, had that for a few years on our bog standard Astra, as said sounded strange at first, but assumed as mentioned they just 'arse covering'.