You need test the cat when it's hot. Take it for a short drive and then use and IR temperature gun and point it at the pipe going into the cat and coming out of the cat. The 'exit' reading should be noticeably higher than the 'entry' reading if the cat is working. The more spirited the driving the higher the temp differential.
(Bank2) Driveside before the cat was 625F and after was 465F
(Bank1) Passangerside before the cat was 623F and after was 501F
(Bank2) Driverside before the cat was 455F and after was 315F
(Bank1) Passangerside before the cat was 495F and after was 460F!
So to me i think its running HOTTER on (bank 1) due to Bank2.
So do you think it is clogged up? Broken?
Idea's, opinion's, Educated Suggests PLZ.