6.2 owners - Dual or Single Flapper

[Rob Mugs]

Just curious if maybe it's a trim level thing?  I have an LT Trailboss 6.2 and only a single flapper.  I've heard many say they have 2?

 

Not really "important" per se, just curious if it was perhaps a lack of them in stock?  They wanted the higher trims to have more sound deadening?  

[JAEDEE]

I had 2 on mine.  2020 Sierra SLT with the 6.2

[mrtizzom]

My 20 6.2 RST has two...did a muffler delete and left both of them.

[SILVER SLED]

2021 RST, only 1 in front of the muffler.  

[SILVER SLED]

The official reason from GM for the flapper is to increase back pressure to increase fuel mileage when in 4 cyl (14-18) or less than 8 cylinder mode.  Not saying anyone has to believe it, just sayin'.  

Edited January 11, 2021 by SILVER SLED

[Robert Mcbride]

2020 at4 6.2 with 1 flapper

[BluegrassMotorsport]

1 hour ago, SILVER SLED said:

2021 RST, only 1 in front of the muffler.  

How strange. My 2020 RST has two. 

[kodiakdenali]

Very strange...2020 Denali, I only had 1 flapper.

now I have 0

[t-bone]

My 2021 TB Custom has two, but not for long. 

[JohnH4260]

19 hours ago, Rob Mugs said:

Just curious if maybe it's a trim level thing?  I have an LT Trailboss 6.2 and only a single flapper.  I've heard many say they have 2?

 

Not really "important" per se, just curious if it was perhaps a lack of them in stock?  They wanted the higher trims to have more sound deadening?  

What is a flapper? Thanks.

[Rob Mugs]

1 hour ago, JohnH4260 said:

What is a flapper? Thanks.

Do you have a 6.2?  If so, hop under your truck.  Near the muffler, you will see a square bolt and spring. 

 

It closes off the exhaust at low rpm to reduce drone while cylinders are deactivated. 

 

So, it seems like it's completely random on if they got one or two

[OnTheReel]

I had two on my 19. From what I’ve seen, all of the 19s had two. 2020 and up it seems random on whether you get one or two. Could be a supplier thing, I don’t know.

[JohnH4260]

49 minutes ago, Rob Mugs said:

Do you have a 6.2?  If so, hop under your truck.  Near the muffler, you will see a square bolt and spring. 

 

It closes off the exhaust at low rpm to reduce drone while cylinders are deactivated. 

 

So, it seems like it's completely random on if they got one or two

Ordered my Sierra Denali last week with the 6.2. I’ll have to check after it arrives in March. Thanks for the explanation.

[Rob Mugs]

43 minutes ago, JohnH4260 said:

Ordered my Sierra Denali last week with the 6.2. I’ll have to check after it arrives in March. Thanks for the explanation.

Here's a better explanation.  Note at the 36 second mark.  Even when wide-open, it's still restricting the flow by maybe 30%

 

[JohnH4260]

How does one delete or get rid of the flapper?