After market cats will not prevent a CEL if you have headers. You'll need an O2 conditioner.

 

Really... PPE advises that my setup is "EPA compliant". JAT, are you calling them liars?

 

When they install your PPE headers, they also install the conditioner which is why you're not getting a CEL. Both PPE and sikky headers are sold with their respective conditioners.

To simplify things, if you mess with the primary cats by either, gutting them or replacing the stock headers with aftermarket ones, you'll need the conditioner.

Your car with aftermarket cats on the exhaust still has higher emissions than a car with its primary cats still in place.

 

Funny, I ended up keeping my exhaust system stock.

$$$$ is going into the new house.