I have an 82 air cooled california vanagon that I've put federal heater
boxes on and a header exhaust system.  I have removed the O2 sensor, but
it has been suggested that my mileage would go up if i reinstalled it.
Here's my dilemna.  The O2 sensor was originally in the crossover pipe
at a point where it was taking a reading from the exhaust out of all
four heads mixed together.  With my current system, the four headers
converge right at the muffler, so there is no way to install the sensor
in a place where exhaust from all four cyclinders has merged. The only
option for putting the O2 sensor back in the current system, would have
the O2 sensor only reading from one of the four header pipes.  I assume
this means that it would be taking a reading from only one cylinder.  Is
this a problem?  Wouldn't this mean that the ECU would alter the
fuel/air mix based on information from only one cylinder?  Should I
leave the sensor off, or put it back in one of the header pipes?  If I
put it back, Hwich header pipe should I put it on?  Does it matter?

Thanks folks.

Greg.