[eschaider]

The AFR gauge is just the equivalent of a computer monitor. All the real work is done by the sensor and its associated electronics. The standalone sensor I like is the NTK sensor.

Unllike all the other sensors that begin to drift as they fail, The NTK sensor just stops working altogether. That prevents you from chasing a failing sensor with your tuning efforts and getting upside down and backwards in your tune.

Most gauges work or can be made to work with just about anything. Use electronics that will support an NTK sensor or buy a whole sensor package including sensor and electronics that uses an NTK sensor. Instrument both sides of the engine so you know what is happening everywhere and the impact your tuning changes have everywhere.

Unspoken earlier but important, make sure you get a wideband sensor, not a narrow band sensor.