adaptive valve in the exhaust.

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j91z28d1

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probably already been asked but I don't see it. so I was under the truck today and noticed my 2011 has that spring loaded exhaust flapper after the muffler. from everything I've seen they didn't start till the next Gen 2014 and up.

is it just a hybrid thing since 08 or something changed along the way.

interesting.
 
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j91z28d1

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this thing
 

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BG1988

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SO i can make it louder by adjusting that screw?
 
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j91z28d1

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there's no screw its just a spring loaded flap. does your 08 have that? seems weird I can't find any mention of its use before the 2014+ Gen.



but yeah, just wait till it's cooled off, start the truck and reach under it and open it by hand before the exhaust gets hot and you can hear the sound change. mine sounded louder. could wire it open if you wanted.


 

dnt1010

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First time I saw the flapper valve was on a 2014 GMC Sierra, I am not sure that it did much other than rattle and squeak after it got a few miles on it. Idea was to dampen the engine drone when it was running in V4 mode.
 
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j91z28d1

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First time I saw the flapper valve was on a 2014 GMC Sierra, I am not sure that it did much other than rattle and squeak after it got a few miles on it. Idea was to dampen the engine drone when it was running in V4 mode.
yeah that's what I've found. mines a 2011 and there's no rattle or squeak at all. just seems weird, makes me think it was a hybrid only thing on this generation. maybe even a better quality back then lol.
 

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