Hi Omar, i dont own a corvette but love to help.
I remember reading that if your O2 sensor goes bad or freaky, it can create a very rich mixture and mess up the Cat. Also, some gas additives can sometimes have things in them that could mess them up.
Really though, it's stuff that coats they platnium fibers in the cat. So if you're running rich, you'll get that extra carbon to coat the fibers and prevent the platnium from catalyizing the reaction.
Get the car computer diagnose not only for exhaust system, but for Intake check, Air flow meter check, fuel pump check etc may be you will find some culprit there. Hope it helps.