Wide band oxygen sensor

Where is the best place to install wide band oxygen sensor. Also is 2 oxygen sensors better than having one advantages-disadvantages. Also i was looking at the banks super gage with option to use EGT sensors. I know u can use 1-12 probes depending on how many cylinders. Also know u can use one my question is if only one where would i want to install into my exhaust. Thinking maybe 2 would be good on my 8 cylinder would i want to install a probe off each header collector. Idk just some things iv been thinking about unsure of. Main reason im asking now is i want to maybe purchase banks gauge or something similar. Want to purchase a the right gauge now instead of the wrong one and having to but another down the road.

Thanks

12Jracer.

If the engine exhaust merges to a single outlet, you can use a single sensor just past the point where the exhaust gases merge. If you have an engine with separate exhaust banks, then you really should have one sensor per bank. Some ECUs can support using one sensor per cylinder, but often that is reserved for engine dyno testing.