May I suggest you also look farther than replacing the cat. A cat should last pretty much forever when the engine is maintained. If the cat has failed it is because the engine is not running correctly. Often the culprit is a faulty O2 sensor that causes a rich run scenario. The sad part is that a bad O2 often will not trigger an error code in the ECM (check engine light).
I am concerned that if you just replace the cat you will be replacing the cat again in short order. Just food for thought.