Catalytic converter code

I have never had a issue with an aftermarket catalytic converter not fixing a cat code. if that was the problem.What is the exact code numbers you have not code descriptions?also, what catalytic converter or catalytic converters were replaced?

Thanks, the code is P0420 Catalyst System Efficiency Below Threshold (Bank 1) and both catalytic converters where replaced.

I just had a bank two catalytic converter low efficiency code on a Ford F150. the way I knew the catalytic converter was bad was I watched the the up stream and down stream o2 sensor readings for bank two. Both sensors were about equal readings at about 2500 rpm. How did they determine it was the aftermarket catalytic converter? also, if you changed the bank two catalytic converter as well and the catalytic converters were not compatible. I would think it would set a P0430 bank two catalytic converter on efficiency. What brand and part number were the catalytic converters?