All the emission stuff on my engine is intact. No issues whatsoever.

 

I am using all 4 but I have extenders on the two after cat sensors. So far it has resolved my CEL issues and passed emissions. My car has a tune and aftermarket exhaust.

 

I just passed CA inspection last week. Here, if you run cat-less, OBD will show there is no measurable difference between the primary and secondary O2 sensors and will throw a "not ready" I/M code, even with the absence of a dash board CEL. Always good to have a stock exhaust available, if that's how you run.

 

Woe to the fool who attempts the required visual in Kali - cats. They won't even bother with an obd scan.

Mine are in the frunk lol