Failed emissions, P0420, bought a Walker direct fit cat from Autozone (best price and actually in stock) ~$260 bucks, then had my neighborhood shop replace it. Passed emissions! I'm curious though... Should I expect improved fuel economy? Smoother idle? Anything?
Usually the 420/430 codes set due to inefficiency at breaking down the exhaust gas emissions and not so much for restriction. You probably won't feel any difference.