Catalytic Converter

Honestly your local laws will dictate what you can and can not do. Here in the DEQ zone I live in its 76 and newer. Now the vehicle is supposed to retain all the factory smog stuff. But, I passed with a built 460 in my truck (my truck was never offered with a 460 in 4x4) with headers, custom exhaust, etc and I passed as long as they saw I had cats nd I pased the sniff test.