catalytic converter

[Markooo71]

Hi all,
I'm Marko, and I'm new here, and I drive a 225 series II. Just wondering if anyone can tell me major symptoms of catalytic converter failure? Over the past few days, I've noticed a drop in performance, when rpm gets up around 4000, and a smell somewhat like bad eggs. I had a similar symptoms with a previous French hatch, and it turned out to be cc problem. Not sure the same relates to the boosted motor in the 225. Any advice would be much appreciated.........Cheers