Move O2 sensors to secondary cat?

[PantsDants]

So I was checking out some local shops for a custom header-back system and I was thinking about the header to go with it. The majority of headers available are catless, and the few catted ones are about 50% more expensive. Plus the general consensus seems to be that a cat in a header is just gonna wear out/clog up really quickly.

Now I'm aware that you can disable the code for cat inefficiency via a tune. But my thought was that if there were a way to extend the sensor wires, couldn't the O2 sensors be mounted around the cat in the front pipe instead? Like I said, I'm looking at custom exhausts, so it probably wouldn't be much of a stretch to relocate the front pipe cat further down a bit and weld some bungs on either side.

Thoughts?

[Fast_Freddy]

The primary O2 sensor is actually a wide range AFR sensor and needs to be located before any cat and not too far downstream. It needs to stay in the header. The secondary O2 sensor is a traditional narrow band sensor and could be placed in the front pipe after a cat. It's probably easier to simply install a CEL Eliminator on the second O2 sensor instead. I've used both the angled version and the mini-cat with 100% success (see below link).

http://www.bigdaddiesgarage.com/

[PantsDants]

Originally Posted by Fast_Freddy

The primary O2 sensor is actually a wide range AFR sensor and needs to be located before any cat and not too far downstream. It needs to stay in the header. The secondary O2 sensor is a traditional narrow band sensor and could be placed in the front pipe after a cat. It's probably easier to simply install a CEL Eliminator on the second O2 sensor instead. I've used both the angled version and the mini-cat with 100% success (see below link).

http://www.bigdaddiesgarage.com/

Thanks for the info. For the 86, is there space enough for the mini-cat adapter to fit? It seems to stick out kind of far.

[Fast_Freddy]

The mini-cat fit my Borla UEL very well but I don't know about other headers. The angled one worked well on my turbocharged XB2 for 4 years and 40k miles w/o a related CEL.