It needs to be PZEV spec'd/certified to have the 15yr/150K mile PZEV warranty on some powertrain, electrical and emissions components. Your car is too old to be PZEV. It didn't start until ~2007.
These cars are only sold new in PZEV States, which KY is not. Your car would have PZEV badging on it and have that stuff listed in your warranty booklet that came with the car if it had it.
Every newer vehicle has a 7yr/70K or 8yr/80K mile Federal emissions warranty on catalytic converters. Unfortunately you're beyond that too.
I assume you're getting catalyst inefficiency codes, but the car still runs as it should and the exhaust system is otherwise intact?
That being the case, I'd install a spark plug anti-fouler in the downstream O2 sensor location. You can Google it for info.. This should eliminate the P0420 code for you and you don't have to spend ~$1200 for an OEM CC assembly.