Mustang catalytic converter on OBD2 car in cali.?

I want to know if addind a high flow catalytic converter such as a flow monster will affect my car. I want to know if it will affect my computer. ALso i would like to know if it will allow me to p smog test in california. Finally i wanted to ask the same question but with deleting the pre-cats. I live in california and have a 2001 mustang v6 with 100K miles. thank you in advance for those who answer my question