which cat to remove

[808Mazda3]

i am looking at getting a set of headers, and plan to take off one of the cats on my Mazda 3 HB.. The only thing is i dont know which one to take off since i am not sure if both of them have the 02 senor.. I do plan to get a high flow cat later down but just for now all i am planning is headers and a cat remove. Thanks for the help..

 

[zoom-zoomhatch]

If either one would be O.K. it would be the second one, not sure but it might also have a 02 sensor.