if you replace the factory header manifold with an alta unit should it pop up a code? Mine hasnt yet! I hope it doesnt but if it does do they make an o2 sensor kit to bypass the sensors? I have the obx exhaust and my car is loud! it sounds good and i like it but the header was a bear to put in!

 

If it has a cat then you shouldn't throw a CEL.

 

I have no experience with this myself, but I think you can install an 02 sensor simulator to trick the ECU into not throwing the code.

There is one in the Market Place currently as well:
https://www.northamericanmotoring.co...ct/3097/cat/22

 

it was the alta header with a cat on it but was just checking. Thanks guys.