<< I'm thinking about monitoring my A/F ratio>>
I should have added that if you intend tuning for emissions then stoich (AFR
14.7)is what you are looking for and a regular narrow band sensor will work
If on the other hand you want to tune for power/performance then you really
want an AFR of around 12.5-13 which a narrow band sensor won't tell you
accurately but a WB02 sensor will.
Most modern ECU's are only interested in Stoich when in cruise (>200RPM,
Hot, Not WOT) so they work fine with narrow band.