what to do with the 2nd O2 sensor?

[CODE4]

I am looking at replacing my WHOLE exhaust on my '99 RS-- header, downpipe, then 2.5" all the way back to a flowmaster. Many headers I have found have the first O2 sensor mount near the block. My stock exhaust is clean so my plan was to keep it when I need to get emission tested. Has anyone else had an exhaust done without the cat? If so what did you do with the 2nd O2 sensor that is threaded in after the cat? I think the ECU might throw a code if I just zip tied out of the way =]

What solutions have worked? Any opinions on if 2.5" is too small/large for nat. aspirated?

[kjewer1]

The second O2 isnt looked at by the ECU the same way the front one is. The front O2 needs to cycle up and down as the ECU varies IPW/IOT to keep the average of the O2 voltage at .5, or 14.7. The cat will soften the cycling a bit, and on the 2nd sensor you'll see a more stable reading. If the cat is removed or fails, the second O2 will cycle exactly like the front O2. The ECU sees this, and tosses a code. The ECU doesnt care what the absolute value of the rear sensor is, just that its steady. So hanging it up out of the way does work if you leave it plugged in. The trouble is getting it fixed in a way that wont set the car on fire, since its a heated sensor I would recomend leaving it outside of the car at least. Personally, I just left it in the exhaust, and after a couple months, its just stopped throwing the code. OThers have seenthe same thing, but not everyone. All of this is for the turbo cars, but since they are both OBDII, there shouldnt be much difference on this subject.

[CODE4]

Thanks much for the insight GSX Racer =]

I also found this link as well to get rif od it completely:
http://www.thefbody.com/~95tsiawd/O2bypass.html
got that from the VFAQ. But thank you for the reply!