Muffler Delete Flapper Question

Krusty · April 13, 2017

if you have the V4 mode tuned out, then remove the flapper. If you do not, leave flapper.

Bam. Lock the thread haha.

My friend owns a muffler shop so I tried 4 different configurations and this is 10000% accurate.

Will the Magnaflow 12909 fit with the flapper in place?

Luster · April 17, 2017

I just went through the muffler delete process. For me it sounded good/deep but it was loud with flapper clamped open and any accleration. On idle it had a good clean rumble. The unclamped flapper made a strange flutter sound so I had to remove. It was loud enough my wife and neighbors could hear me come from slightly down the street and on highway you definitely had more cabin rumble noise even without v4. So I removed flapper and resonator also and added back in a Magnaflow 12909 22" muffler. This seems to be more my style. Nice low growl, calm in the neighborhood, but nice when you lay into it, I barely have any v4 chopper noise with this setup. Everyone on this forum has a different level of what is acceptable sound and for some it will never be loud enough. To note as well I have an AFE CAI on the truck and feel it does add to the sound as well. Keep that in mind if you plan to upgrade your intake as well. Good luck on finding your sound.

Sent from my Note 5 using Tapatalk

Very well stated.

I've had people say, "This is too dang loud! How can you stand it?!"

And Others say, "I thought you were going to put exhaust on this thing, I can't even hear it!"

Weaverstreet · January 1, 2020

I still own a 2000 Mustang GT with a Kenne Bell Twin Screw 2.1 kit and recently replaced the Flowmasters with some quieter mufflers because it was just too loud. They were the first mod I did to the car back in 2000 and now I'm a little older and wanted to hear the radio. I do remember Ford made mufflers for the old FR500 Mustang M-5230-M58 that were quiet until you open it up and a flapper inside the muffler would activate. I would definitely consider something like that for my 19 Silverado. Nice and subdued until you get a little rowdy.

Weaverstreet · January 4, 2020

Just came across this

On 1/1/2020 at 9:17 AM, Weaverstreet said:

I still own a 2000 Mustang GT with a Kenne Bell Twin Screw 2.1 kit and recently replaced the Flowmasters with some quieter mufflers because it was just too loud. They were the first mod I did to the car back in 2000 and now I'm a little older and wanted to hear the radio. I do remember Ford made mufflers for the old FR500 Mustang M-5230-M58 that were quiet until you open it up and a flapper inside the muffler would activate. I would definitely consider something like that for my 19 Silverado. Nice and subdued until you get a little rowdy.

T-Town-Z · January 5, 2020

On 1/30/2017 at 5:34 PM, tjd2003 said:

Interior sound is mild. It sounds about the same as the stock exhaust on my wife's 07 Yukon Denali with the 6.2. For some reason GM decided these newer vehicles needed to be quiet. I felt like I needed to undo that haha. Under normal driving its barely louder than stock inside. Under acceleration you can definitely hear it. I installed the Range AFM module to turn the V4 mode off. When it switched to V4 it sounded terrible, but I removed the flapper with mine as well.

LOL ....As said earlier, EVERYONE has their own thoughts on what's loud. I just did the muffler and flapper valve delete and left the resonator, earlier this week, and as a side note, my V4 is turned off.

My thoughts are that at start up, it sound awesome ! In drive but idling, it sounds great. Accelerating, it sounds freakin fantastic. But .... just running down the road at minimum throttle, it has an annoying drone inside the truck. Mine has the 3.42 gears IIRC, and with a light load, I just don't like how it sounds or feels. My own opinion is that it may have lost a bit of low end torque by opening up the exhaust, and it almost sounds like its bogging down until it gets up past about 1300/1500 rpm. I haven't run it long enough yet to be sure, but I also may have lost about 1 MPG from what I'm seeing so far. I've had a hand held tuner but have not loaded any tune on it yet, just turned off the V4 and corrected for the tire size. I plan to load one of the tunes soon, but wanted to get a good feel for it currently, and to better see what the MPG's are doing. If nothing else, I may put a shorty (maybe 14-18 inch) straight thru glass-pack or Magnaflow on it to bring the drone down to where I like it.

Edited January 8, 2020 by T-Town-Z

Weaverstreet · April 25, 2020

I tried the flapper clamped open and I feel that the throttle was a little dead off the line like that so I unclamped it and the response returned. I'll wait for a programmer especially one that lets you adjust the rev limiter/ shift points. The truck shifts way too soon. My 07 with a 4.8 and 35 inch tires was shifting north of 6k and it really woke up above 5000 rpm.