Removing Cats, O2 Sensors?

Currently own a 1999 Audi A4. Having many exhaust problems due to rusting out. Bad sound.
I am going to straight pipe right to the muffler, removing the two catalytic converters. What do I do with the two O2 sensors? Let the, hang, or cut them off? Will this greatly affect gas mileage?

I am not concerned about passing emissions.

Thanks,
Zach

You cannot run any PCM controlled engine without the O2 sensors.

And if your A4 has the turbo 1.8L, you really don't want to run without O2 sensors since having an incorrect Air/Fuel ratio on a turbo car can cause expensive engine issues in a hurry.

-Rod