High fuel trim on bank 1 causing P0420 code?

No, but if you really wanted you could just plug in one side.

 

Could be a wideband o2 sensor.

 

So I found out the boxes were just a Bosch "smart link" to get your plug on their sensor.. I've heard not using Denso could throw the code, so I switched the sensors, thinking it would just be the one that the computer doesn't like, but I got the same code after the 2 drive cycles. So I think it's gonna be the simulators at least for now, as I've already spent enough in cats for my taste. My guess now is that the cat I got was bad. Fortunately the guy I got it from is willing to refund me based on my evidence that it isn't anything else. Here in the Salt Lake Valley we have some of the worst air in the country due to inversion in the winter, I cant justify hollowing out the cats with this air, but at the same time I don't feel bad if my cats are only performing slightly under efficiency, when the alternative is new $750 cats. Thanks all for your help, I'll update after the simulators are in.