Why the third catalytic converter on my 2011 5.3 Silverado? 02s are behind the two on each side so what's the purpose of a third downstream? Maybe it's a resonator?

 

How far downstream? If it is a 3rd cat it will be as close to the y-joint as possible.

 

Excuse me, sir. I was "pretty sure", but I stand corrected. It's tough when you own two '05's.

 

I would think if it was a third cat then there would be an o2 sensor behind it to monitor it.. I think you have a resonator.

 

Its a catalytic converter. When I cut mine off, it had the honeycomb and everything.

Don't post if you don't know....

For those that haven't seen it:
https://www.performancetrucks.net/fo...t-pics-436526/

 

I have seen that on a friends truck and was pretty sure it was a cat. Just didnt understand why GM needed a 3rd one

 

Here's a pic of the cat or resonator or what ever it is. It really looks like a cat although no 02 sensor downstream of it. There is a flexible joint just after which you can barely see in the pic.

What ever it is, is it really necessary? Would I get a drone sound without it? More power would be nice!

 

Now I see the pics of yours. Yours was a cat so most likely mine too. Seems some just gutted theirs. How hard a job and how much effect to sound?

 

Its not monitored but GM has been installing post cat cats for some time now and doesn't monitor them. Maybe all the oil being burnt by their shitty PCV system was more then the two cats could clean up so they had to add a third?

 

think they've been running that setup since 09 I believe. I know some people have just gutted it, but I've also seen a few that have deleted it altogether. I would think since its not monitored with an 02 sensor, that it could be removed without any issues.