Also, with a 4-wire sensor it's so easy to run power to the sensors and get them to operating temperature. Just one wire to switched 12VDC and one wire to ground. As the sensor heats up the resistance goes up and current flow decreases to almost nothing, so there is no need for a control circuit on the O2 sensor heaters.
I have been doing this for decades. Chrysler never had a control circuit for O2 sensor heaters (can't say on newer vehicles though) key on and blam the sensors were always powered.
For someone not pushing the ragged edge and on a budget narrow band is fine and for $30 and some junkyard parts you are in business. I did push the ragged edge for years at 20+ psi with nothing but narrow band and was very successful at it and it is a far less forgiving environment then n/a applications.
