[Wayne 962]

As long as your engine is running fine, then having it on one bank should work fine. It measures percentage, not total O2, so it's not going to care that only 1/2 of the exhaust is there.

I would place it on the muffler side, as close to the engine as possible.

Newer cars run 2 or more O2 sensors, especially if they are separated into two exhaust paths like the 911. This gives you an indication of whether or not a bank of cylinders is performing well or not.

You should not run your car without the O2 sensor, as it will be running at an improper mixture. Any HP gain you would have gotten from the SSIs will be lost because the mixture will be way off.

-Wayne