not sure about in arizona...how are your smog laws, and is there an O2 sensor in between or after the 2nd cat on the harness? If there is only 1, I wouldn't worry about it, just a highflow cat or whatever will pass your emissions test. if there are 2 or more, I'd run an aftermarket OBD2 cat.
edit: he beat me to the post. looks like there is an o2 after the first cat, so you need an OBD2 cat on it.