Just bought set of obx headers, racing cats and x pipe..1 3/4..for an ls2..do i need the o2 extension cables for the front and rear? Thanks in advance

 

Just the fronts/post 02's, and you are not going to use the rear O2's and the rear 02's will delete out with the tune (read plug the rear O2's threads sockets with some sets screw type plugs with teflon tape).

If you are not going to have the car tuned where the post 02's can be deleted out in the tune (which would be a wasted, since your giving up a lot of HP without the car tuned for the headers), then you will need to get rear O2 extender cables as well so you can install the rear O2' sensors after the high flow cats, and install the rear O2's with antifoulers.
Note, run the extender cables through the top of the tunnel plate, drill a small holes in the tunnel plate and drop them down out of the tunnel as close to the post O2's as possible. If you run the extenders down below the tunnel plate back to the rear O2's, bank that you will end up melting one or both of the extender cables real quick.
http://www.bigdaddiesgarage.com/angled-cel-fix.html

With the high flow cats so for down range from the heads, and the high flow cats not working as efficiently as the stock cats, there will not be a big enough difference between the pre and post 02 readings, and the car is going to start to throw codes without using the antifoulers.

 

"Antifoulers" ? ?

I am confused what you mean by antifoulers.

In my case, I have a 2011 GS with a set of Pfadt headers and a Pfadt x-pipe with cats.

My after-cat O2 sensors have been removed (and the bungs plugged), and the PCM was programed not to throw a check engine light or a code for those missing rear O2 sensors when it was dyno tuned.

Do I need "antifoulers" (whatever they are)? .... or am I just confused as to what you posted?

Thanks,

 

Just referring to L-shaped adapters for your rear O2 sensors should you not get a tune after headers. The "anti foulers" allow the rear O2 sensors to show a significant enough difference to the front sensors so that the computer does not think anything's wrong.

Sounds like you already have it covered.

 

Ok ... never heard of "antifoulers'

 

In a very generic sense, the PCM looks at both the front O2 sensor and rear O2 sensor and compares the difference between the two. If there is a difference, the PCM concludes that everything is okay and the cat is working.

However, if the PCM does not see a difference between the two, it concludes that there is a failure. So, in order to fool the PCM after a header install, you can move the rear O2 sensor away from the stream so that it registers a different value than the front O2 sensor.

One way to do this is to use an "anti-fouler" which was originally designed to move an O2 sensor away from the main exhaust flow to isolate it. This technique has since been used on rear O2 sensors typically after an aftermarket header install to fool the PCM into seeing a difference between front and rear O2 sensors thus, a functional system.

However, it is redundant since the Corvette PCM is programmable to omit the rear O2 sensor warning and all the matters is the front O2 sensor anyway. No need for "anti foulers" if you get a tune and if you've spend $1500-$2000 for an aftermarket exhaust, no need to skimp on the tune.

 

I ran both sets for about 6 months after I installed by ARH with Cats.. No codes, no problems. When CoW tuned me again, he pulled the rears and tuned them out... just fyi.

 

I was able to get enough length on the fronts by just pulling the tape off of the existing harness and pulling the o2 wires out with my OBX headers. I retaped it and secured everything after.