I have one of the Bus Depot catalytic converters that has the  hole for an
O2 sensor (it comes witha threaded plug).  I have thought of installing a
second O2 sensor in there for diagnostic purposes.  I assume this location
would give a reasonable reading, as it is on the inlet side of the cat?
The plug is probably impossible to get out now, but I may put a wrench on
it the next time I am under there.  It would be nice to run a wire up front
and read the voltage output as you are driving.  I have done this with the
stock one, but you  get steadier readings with it disconnected from the ECU
and that kind of defeats the purpose.   Anyone already done this?

                                                            Jay  '85