Stock exhaust system components

Adambraaaps · January 9, 2019

So on my 18’ Silverado I can see there are 2 parts, one looks like a big muffler and the other smaller one after the muffler a resonator. Am I correct?

SirenRed16 · January 9, 2019

Yeah you're correct. There is also a flapper valve right behind the muffler.

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3tspapat · January 9, 2019

FYI. On 2018 the flapper is before the muffler.

TRKLGND · January 11, 2019

On 1/9/2019 at 11:29 AM, 3tspapat said:

FYI. On 2018 the flapper is before the muffler.

Not on my 2018 DC 6.2L. It is most certainly after the muffler.

ftwhite · January 11, 2019

Same here. On my 2018 6.2 1500 CC, It goes cats, y-pipe, cat, flex joint, muffler, flapper, resonator, tail pipe.
The flapper might even be considered part of the OEM muffler part.

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3tspapat · January 11, 2019

For the 6.2s I guess. I have a 5.3. I think OP has a 5.3 as well.

Jaychevy81 · January 12, 2019

I have the 5.3 stock had the flapper before the muffler.

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Bmech · January 12, 2019

My 2018 6.2 has the flapper after the muffler.

3tspapat · January 14, 2019

Wait!!! I also have a flapper in the passenger seat but only on the weekends and only when my wife is in the car

ftwhite · January 14, 2019

For the 6.2s I guess. I have a 5.3. I think OP has a 5.3 as well.

I think the only thing that matters is the cab type and bed length. 5.3and6.2 are same part number. As far as I can tell from pictures, if your flapper comes before muffler, you have a after market job. Machanically, I am not sure why that would work anyway. Reducing flow or pressure to the muffler would be odd... But maybe.

https://www.gmpartsonline.net/oem-parts/gm-f-muffler-84327965/?c=Zz1leGhhdXN0LXN5c3RlbSZzPWV4aGF1c3QtY29tcG9uZW50cyZpPUdIMTQyNDA1JnI9bGF5ZXJfNCZhPWNoZXZyb2xldCZvPXNpbHZlcmFkby0xNTAwJnk9MjAxNyZ0PWx0eiZlPTUtM2wtdjgtZ2Fz

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TRKLGND · January 14, 2019

On 1/11/2019 at 5:06 PM, 3tspapat said:

For the 6.2s I guess. I have a 5.3. I think OP has a 5.3 as well.

Yes, the OP has the 5.3 or the V6. His signature says he has an LT so he can't have the 6.2L.

3tspapat · January 16, 2019

hey let's stir the pot some more! I was checking out a 2017 Sierra...the flapper was AFTER the muffler! I think they just put it wherever they want it. Pretty soon it will be before the third cat. Heck maybe after the MAF in the air intake.

ftwhite · January 16, 2019

I bet the ones before the muffler are for back pressure, and the ones after are for sound. Just a guess though. It seems they changed the design of the exhausts in 2017.