3on18's

I've sourced out and OBX long tube Racing header for my 09 Mazda 3. Does anyone have any experience installing one on these cars? I know the catalytic converter is part of the original exhaust manifold. The header has an o2 port on one of the tubes. Would I be able to weld in a different cat after the header and extend the o2 sensor wires so I don't run into emissions troubles or an MIL?

Any input is greatly appreciated!

I'm a mechanic so I know what I'm doing with cars. Just want to clarify if anyone has done this mod yet and what issues they have come across.

3on18's

No one has put a header on???