02 bung

So 3" exhaust has a test pipe welded to it. I'm gonna have to cut it off to put the cat back on and drill a hole to weld in the o2 bung behind it.  I'm assuming that it doesnt really matter how far back to weld it in?  or is there a certain distance back from the catalytic converter?

Are you putting a normal o2 back in or a wideband set up?

w/ the motor he's got it better be a freaking Wideband!

well i'll have a wideband, but doesnt that o2 sensor go onto the o2 housing? or am i mixed up?

no the wideband goes on the downpipe or test pipe area

ah, gotcha, ok well either way, is there a certain distance behind the cat that i need to weld the bung in?

i don't think you should put it behind the cat.  i'd put it on the downpipe that way you can get a good reading on what exactly is coming out of your engine.

right, but this has to be streetlegal and pass emissions testing... so does that mean that i'd have to add a 3rd o2 sensor? One on the o2 housing, wideband on the downpipe, and one behind the cat?  Cause the one behind the cat is the one that matters to pass emissions