72 mfi o2 sensors
 

What is the best location for O2 ssnsores? Kn the muffler after at the connections or on the header before the connections?

About 4 inches downstream of the collectors. Clocked somewhere between upright and horizontal, but not below horizontal or the it may be damaged by temp swings from water condensation.

Wideband O2’s don’t like rapid temp swings.
Also very important to use the deep bungs, so it isn’t protruding into the exhaust stream or it will die early from overheating.

Thank you

02 sensor
 

How is it hotter in that collector than in a cat on a 3.2 Carrera. The Carrera is not wideband, so is there a fragility in a wideband but not in a 1 volt type. I do have to keep replacing them on my track car, which I attributed to race fuel and a rich condition.
Bob

Yes. Narrow band O2 sensors aren’t as fragile and sensitive to sudden temp changes.
Plus the O2 is before the cat.