leave flapper valve or not

[J_Mas6.2]

Installing a new magnaflow exhaust next week in place of the factory muffler.  can the flapper valve be left on or does it need to be removed?

[tbarn]

Leave it on unless you intend to tune it or use a Range device. I just did mine as muffler replacement only. It was too quiet so I clamped the valve open. Helicopter noise. Unclamped it and removed  the resonator. About same effect on noise level. Happy with it now.

[Centex14]

Remove it.  Mine's open and I have no idea what this helicopter noise is.  Never heard it before with borla's.  Now it's tuned out and I don't worry about it.

[Ozer]

I just got the Carven TR muffler welded in, took the flapper out and sounds great.

I turned the AFM on just to see what would happen and in V4 mode it sounds like a military chopper is following you lol Very annoying.

If you plan on leaving V4 on then keep it. 

[Sierra Dan]

There is no need for the flapper if you plan on Deleting the AFM to run full V8

[Ozer]

2 minutes ago, Centex14 said:

Remove it.  Mine's open and I have no idea what this helicopter noise is.  Never heard it before with borla's.  Now it's tuned out and I don't worry about it.

When you are on the highway and it kicks into V4, the noise is basically Bop Bop Bop Bop Bop Bop and when it gets back to V8 then you hear the full exhaust tone like how it should sound.

[Sierra Dan]

Basically the "chop" or flutter sounds like a muted version of an old Huey Helicopter.

 

Here is an example starting at about the 50 second mark:

 

https://www.youtube.com/watch?time_continue=76&v=UzDNgaZzt1s

[MN1(SW)]

I removed my muffler and the valve and just welded a piece of pipe in their place. It sounded great to me and V4 really wasn't that noticeable. Not to me at least. If push comes to shove, you can always just leave it and lock it in the open position with some with some wire or something. If you don't like it, you can always close it. 

[Centex14]

57 minutes ago, Ozer said:

When you are on the highway and it kicks into V4, the noise is basically Bop Bop Bop Bop Bop Bop and when it gets back to V8 then you hear the full exhaust tone like how it should sound.

Never heard it.  

[Ozer]

40 minutes ago, Centex14 said:

Never heard it.  

What muffler you have?

You wont hear it unless its in V4 mode and flapper can move freely. 

[ftwhite]

I replaced factory muffler with a Magnaflow. Deleted the flapper, but left the resonator. Only noise I hear that is new is under light throttle loads on the freeway (like on slight uphill). Other than that, it just sounds better and super quiet in V4.   

[Ozer]

5 minutes ago, ftwhite said:

I replaced factory muffler with a Magnaflow. Deleted the flapper, but left the resonator. Only noise I hear that is new is under light throttle loads on the freeway (like on slight uphill). Other than that, it just sounds better and super quiet in V4.   

Perhaps the design and size of the muffler makes a difference. What model/part was your muffler?

Mine is Carven, straight thru design with no baffles or anything . That may be why it sounds choppy in V4 and i have the resonator in place still.

Edited November 9, 2018 by Ozer

[Snowcamo]

I replaced factory muffler with a Magnaflow. Deleted the flapper, but left the resonator. Only noise I hear that is new is under light throttle loads on the freeway (like on slight uphill). Other than that, it just sounds better and super quiet in V4.   

Hey what was that MagnaFlow part number?

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[ftwhite]

https://www.magnaflow.com/products?partNumber=12909

12909

[GMC_SD_Ult_16]

I removed oem muffler, resonator, and valve and replaced with a 12909 Magnaflow on my 6.2L. Been super happy with sound and don't notice the annoying sounds described by others.

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