I am looking at having to replace my cats (I believe they are clogged, a different story).
Looking on e-bay I can find replacement 4 cat systems for about $550.

I have seen high flow cats for a whole lot less, but not sure if removing the 4 cats and replacing with 2 is legal in Harris County.
I don't mind the 4 cats, but if I can get 2 cats installed at a local shop for ~$200 vs $600 for the 4 cat setup and still be legal and pass inspection/emissions I would rather do that.