Flapper Removal Questions on 2019 Silverado 6.2L V8

[MAK2013]

I have a 2019 Silverado LTZ with the 6.2L v8. My previous vehicle (2012 Tahoe LT 5.3L) I chopped the exhaust and added a magnaflow 12589 with dual exhaust tips. It made the perfect tone, loud but no drone at highway speed, something I want to recreate to an extent with my Silverado 6.2. Back in 2012 I guess the 5.3L Tahoe didn't have flappers. The new Silverado has 2 flappers, one before the muffler and one after. I have ordered a Magnaflow 11229 to replace the stock muffler with. My question, which flapper (if any) should I remove to get the best/deepest exhaust tone without making the vehicle drone when AFM kicks in. I want a deep sound without making it obnoxiously loud or making it drone at highway cruise speeds. I've seen a few posts from people who removed both flappers, only to have them both welded back in place. If I remove the flapper before or after the muffler, which one is going to give me the best sound without drone?

May be useful to mention I also have an AFE Momentum GT Pro 5R CAI installed (one of the perks of working for a truck upfitter is getting parts before they're officially released!). Any advice helps

Thanks for the help

[S9779]

I recently had a borla muffler swaps in the stock location leaving both Flappers in. I'm glad I did because I can still hear the faintest hint of the strange tone when cruising at low speed and active fuel management kicks in. Over all time very happy with the sound nice deep sound when you get on it but you really can't hear anything when you cruising on the highway.  

I did not want a constant obnoxious sound just wanted to be able to hear the v8 I paid up for. 

Edited February 3, 2020 by S9779

[BillCT]

which Borla muffler did you get/ Thanks

[MAK2013]

I’ve heard good things of the Borla Touring muffler for the 6.2L. For what I’ve heard the S type muffler is too loud and drones on the 6.2 at 40-60mph

[S9779]

I ordered a pro xs muffler off Amazon borla muffler 40359. Don't know what line it would be compared to. It was in only 90 bucks so I think it'd a lesser line since I have seen the atak mufflers go for 250. But since I'm under 200 bucks all in I could not be happier. 

[Bratbowtie]

Just bought Sierra 6.2 what happens if you block both flappers open or 1 at a time, my buddy has a 2010  6.2 it sounds great on start up and low speed but dosen't blow you out at highway speeds either. I know it's a different beast but the tone is very mellow and deep. that's for me

 

[MAK2013]

Binding both open will just make it drone, just as if you cut both of them off. Personally I’d just cut one off and leave the other alone

[EricTheRed]

From what I’ve been reading on this forum 6.2 guys are having success with changing the muffler and removing only the downstream flapper.

[kevant69]

With my 6.2 I am wanting to do a muffler swap but may remove the 2 resonators and leave flappers in. I haven't seen any post on just a resonator removal. I would like to hear a sound clip of stock with no resonators.

Sent from my SM-N960F using Tapatalk

[AsapAT4]

Did you end up doing this? I want to do a muffler replacement or delete but don’t want drone. I don’t need anything crazy loud like the atak although it sounds amazing

[EricTheRed]

Is there any drone at certain rpms, uphill, under throttle? 

Edited August 23, 2020 by EricTheRed

[TNTSierra]

If you guys don’t want drone you gotta step up and get a full cat back. Borla, Corsa are 2 that have none. The Gibson on my old 2018 6.2 had almost none. Very faint. I just put my Corsa on and I can’t believe how much better it sounds, ZERO drone at highway speeds, and the restrictions the factory flappers have on the stock exhaust is ridiculous. It covers almost 50% of the exhaust.  The truck accelerates much better, and when cruising down highway and setting cruise, my instant MPG gage was reading 2+ mpgs better than when I had stock exhaust.  Just save up and do it right. Just my opinion. I waited 4 months kicking around whether to spend the money. I am so glad I did it. Now just waiting on the CAI. 
good-luck gentlemen on your decisions 

[franktrusty]

I believe removing the flappers alone would increase performance. And there are ways to keep it in 8 cylinder mode...

[TNTSierra]

1 hour ago, franktrusty said:

I believe removing the flappers alone would increase performance. And there are ways to keep it in 8 cylinder mode...

Yes removing the flappers will increase performance but if you want that and Zero drone. Why not just get a catback from Borla, Corsa or Gibson??

The Borla and Corsa are around $1300+ but the Gibson can be bought for half that and it’s a very good exhaust. I had it on my 2018 and it sounded great.  They just didn’t make it for a standard bed on T1s otherwise it would be on my truck.  That’s how much I liked it. 
Just my opinion but I’d rather do it right that hack up the stock exhaust and then still have drone. 

[flyingfool]

i left my flapper in, just locked it in the open position with 2 fender washers and a 2.5" long 1/4-20 screw. i found a thread on here that shows you how to do it years ago. i believe it was also a tsb update by GM tech to reduce truck fires caused by the flappers stuck closed