As title, which is the Lambda sensor for use with Megasquirt or Omex/ Emerald ECU?
I'm guessing wideband, but have seen ones advertised with up to 5 wires.
Having the manifold modded and thought I would have a boss welded in at the same time.

I can only help with regard to MS.
The lambda sensor doesn't connect directly with MS unless its narrowband AFAIK.
A wideband sensor needs a controller to interface between sensor and ECU.
I have a Tech Edge wide band setup. It has four wires from sensor to the controller but only two to the ECU.
Connection was simple and it works spot on.

Geoff