Header fix?

I am buying a header for my car and was wondering where the thread is to fix the engine light is at? Actually, all i need is to know what part it is that is used to fix it. I remember that you drill it out to 1/2 inch and then your O2 sensor goes into that, but cant seem to find the thread. Can someone help me out? Hopefully someone can make since of what i am saying.

Anyone?

Are you talking about an O2 sensor fooler/bypass?
This?
https://www.thegalantcenter.org/show...sensor+headers

YES!!! You are the fucking man! I couldnt remember what they called them (the spark plug anti-foulers). Now one more question (and this is just to clarify). When i install this it goes to the O2 that is at the pre-cat delete (second one on the exhaust), right?

I don't know for sure,,but from what I read I would think so (that it goes on the downstream O2 sensor like you said).