Rear o2 sensors disable

[dsg2003mach1]

What exactly does this disabling of the rear o2 sensor(S) do for you? Please advise, Thank you.

the rear O2s are there to monitor performance of the cats. If what they're seeing is out of range it'll throw a CEL so you have them inspected. Relocating them, deleting them or replacing them with high flow units will end up throwing a CEL even though there's technically no problem. Turning them off with a tune can cause issues with inspections. Using a non fouler as a spacer can bring them out of the exhaust flow enough they don't trip a CEL.