I just realized these are for the right hand side only, but of course you could install one on the left side outside of California emissions areas. If you need the left hand side it is part number 81712.
Application list in the executive order document:
https://ww3.arb.ca.gov/msprog/aftermkt/devices/eo/d-182-47.pdf
So I can sell them separately at $300 each.
You can search around for prices. I think I have them at the best price. They are $368.79 from Rock Auto right now.
These are the next best cats after factory. They’re suppose to last at least 5 years / 50k miles. The 49 state ones only last a year or two.