This is, certainly, much ado about nothing. Narrow-band sensors are only accurate about 0.5 on each side of stoichiometric. If you're already there, then they can be helpful.
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.
As far as wide-band vs. narrow band, when the cheapest wide band sensor was $200, maybe it made sense to just have one. But nearly every new car has them, they many times have a U-shaped connector plug and 5 wires, like my wife's Hyundai. The new sensor is around $100 from Rock Auto. For the JY scroungers, many of the 4-cylinder FWD cars have the O2 sensor stuck right in the middle of the exhaust manifold, right on front center of the engine. Pull it out by opening the hood, no crawling around on the ground.
This is an area where a newbie will be better off spending a little more time to get a product that is more user-friendly. Two sensors, data recording and playback can make life much easier for the novice.
One more thing: How many of you think that the right side of the carb feeds one side, and the left feeds the other side? In the case of long rams, yes, in the case of divided single planes, yes, in the case of my Weiand 7503 for the 318 Poly motor, yes, and for virtually everything else, NO. So the right bank exhaust is a combination of the right and left sides of the carb, as is the left bank exhaust. As was alluded to above, fuel distribution can cause many discrepancies from cylinder to cylinder and side to side.
Back in the day, the Direct Connect engine books were full of instructions on epoxying popsicle stick dams in the intake plenum to even out fuel distribution. Older data that I saw showed that most aftermarket intake manifolds had worse fuel distribution than the stock intakes, and as emissions laws got stiffer, the manufacturers stayed out in front. Port fuel injection cures a lot of those ills.
R.
