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2011 GMC 1500 - 3rd Cat?


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3rd cat. Probably to further clean exhaust gases one last time before they exit the exhaust. Or because California said so hahahaha. It is unmonitored by the ECM (no pre or post oxygen sensors or anything watching it).

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Its your resonator....you have two cats, one on each side behind the exhaust manifolds. Pipe from the drivers side joins the passengers side making one pipe, next it feeds to the resonator.

 

Resonator just helps keep drone and exhaust noise levels down inside the cab, not really needed. Truck will run fine without it, just louder.

 

Daniel

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Its your resonator....you have two cats, one on each side behind the exhaust manifolds. Pipe from the drivers side joins the passengers side making one pipe, next it feeds to the resonator.

 

Resonator just helps keep drone and exhaust noise levels down inside the cab, not really needed. Truck will run fine without it, just louder.

 

Daniel

 

I have a 6.2 in a 2013 & the resonator for it is in back. Granted the exhaust is different between the 5.3 vs 6.2. Where that pipe comes together, *I think* there is some mat stuff to reduce emissions or sound. There is also some flex wrap that have been told was to reduce vibrations from exhaust to chassis. Have not cut mine open, but cannot imagine it being shaped as it is to be hollow. Am sure there are photos of exhaust replacement within this forum somewhere.

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Thanks Gang. I had they pipe replaced under warranty on my 2004, and remember there not bring a third.

How much louder would it be without?

Not touching the exhaust till it needs to be done.

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Thanks Gang. I had they pipe replaced under warranty on my 2004, and remember there not bring a third.

How much louder would it be without?

Not touching the exhaust till it needs to be done.

 

Tried finding sound clips on youtube, but generally there was a complete before & after cat back install.

Cannot imagine the sound would change drastically. If anything it may add some cackle when decelerating.

 

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