Don: am I reading one of your previous posts incorrectly? Is the O2
> bung on your exhaust only on one of the 2 primary pipes?
>
> Neil.
>
  Yes, mine is in one of my primary header tubes.  Yes, it only reads the
gasses coming off two of the four cylinders, which still seems to work
fine.  I should have it beyond where the header tubes merge in order to
give the ECU an average of all the cylinders gas output, but that is not
very feasible in my setup.  I can tell, anyhow, when one of my four
cylinders isn't working properly, by sound, by power output.  The injectors
all fire at the same time and for the same interval anyhow, so what you get
from any Digi 02 sensor is simply an attempt to make the average exhaust
output come out at Stoichmetric ....(always wanted to say that word)   If I
have a poorly running cylinder that empties into the tube with the o2
sensor, it will make the other ones run poorly.   If I have an bad cylinder
in the ones that empty out of the un-monitored tube, the motor will run
poorly...
  that's my story and I am sticking to it...