[Sabertooth^2]

Power for my gauges I pull off the 12v outlet circuit in the cabin

Best placement is 12-24 inches behind the merge pipe, being NA you want to be on the short side, and high power FI far. So about 12 inches from the merge is great on these. There's room without your valved setup, but be careful not to hit the floor when the exhaust moves or it'll rattle. Also be sure the sensor itself faces downward to some degree so water condensate doesn't run up into the sensor.

From how you describe it, putting it a couple inches after the merge may be best if you have the space. If it's only reading on one bank's exhaust, you'll want to run two sensors to get the full picture as you may get a rich/lean condition on one bank someday, and it won't be affecting both. But a sensor after the merge shows you that one of the two banks still needs attention if not both. One sensor per bank is nice, but a lot of gauges.

 

[Sabertooth^2]

Yes, tip downwards, wires up

 

[Sabertooth^2]

Perfect. Which fuse do you usually pull off of? The cig lighter? I need the least noisy one

Yep. There's only noise on that if you have something high power in the outlet with a wave pattern anyhow. And you don't need to share that ground. I just ground to the chassis.

 

[Sabertooth^2]

Before it but close is fine