The defouler goes on the post cat O2 bung, not the pre-cat.

The only thing the post cat O2 does is make sure the cat is working properly.....if you put a high flow cat on or remove the cat, the post cat O2 sensor will think something is wrong with your Cat and trip the CEL.


This has nothing to do with performace, hell even the pre-cat O2 doesn't have anything to do with performance at WOT.

Buy the header, buy a defouler....done.

 

just disconnect your battery and reconnect to make the cel go away