[cmracing]

Originally Posted by pbp1

on the location of the o2, it will definitely read leaner in a slip fit collector than it will in a primary even at higher tpm and under load, but it takes having 8 o2s plus one in each collector to see that. I have seen an average of one point leaner reading in the collector.
This doesn't mean that the collector is not an ok place for the sensor, you just need to know that and set your a/f targets accordingly.

at the end of the discussion, all that matters is that you find what a/f reading makes your car run the best no matter where you put the sensor.

amen!