question about o2 sensors, CA spec has two, I want one Options

[6strngs]

I have a CA spec car... this means, my car has 2 o2 sensors instead of one. when I go turbo (hopefully very soon) I'm sure the downpipe will only have a slot for one o2 sensor... so, is there like a resistor or something I can do so that my car doesn't freak out from only having one o2 sensor?

[alltracman78]

Personally, I would recommend a 3".
Especially with FWD.

Yes, if you mount it in the DP before the cat it will set a code.

Your cat changes [catalyzes] the stuff in your exhaust to different amounts, and creates some new ones.
One of the effects is it smooths out the rich/lean.
That is what your ECU is looking for to ensure the cat is working right.
If it sees rich/lean on the 2nd sensor it will set a code.
For OBDII it's PO420. I don't know off the top of my head if you will only get an O2 sensor code, or if you will get a specific code for the 2nd sensor.

You will probably have to extend your wiring to do this.
I suggest you solder it well. This will help prevent that code in the future [less chance of the connection becoming bad].
Also, protect the wires well. Keep them away from the exhaust pipe and cover with some type of tubing.