what side should the wideband o2 go on with twin turbos? is one bank generally leaner than the other?

i could put it in my x pipe but that would be after cats..

 

Put a bung in each side, get a plug for the one you are not using. Do you wiring so you can move the sensor.

Get your tune rough/safe - then do some pulls with it in one side, then the other. If one shows up leaner than the other, leave the sensor in the lean side and tune based from your readings there.

 

How far away from a heat source (turbo) should someone place a wideband? I was thinking 1-2 ft should be far enough away, shouldnt be a problem going too far away either since its a heated element.

 

1-2 is fine. Yes if its heated it doesn't rely on exhaust to heat it, and the suckers are tough too. I ran one @ 2 inches away once with no problems.... I don't know if extreme temps affect the readings though.

One of the ideas with not getting too far away from the turbo is the bigger the distance from the head, the more likely to have a leak in front of it. Fresh air is the enemy here. Also if running it close to the back of the exhaust, you would run a chance of having fresh air mix in.