Muffler Delete / Drone?

Replaced the muffler with a crate Borla ATAK, deleted the flapper, and left the stock resonators. In L9 at highway speeds, there is a serious drone around 1500 RPM. Very annoying especially for anyone in the back seat, and conversation between the front and rear is a challenge. I love the sound, but the drone is an issue on highway excursions. I am currently searching for a solution to the drone.
imo, there was no need to get rid of flapper.
 
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Might want to delete muffler and run Magnaflow ir Borla straight pipe.
 
Late to the message thread but I just deleted the muffler on my 23 ZR2 based on this thread and love the sound. No drone at all (left flapper and resonators as well).

I’ve installed cat back systems on 2 trucks and a newer camaro (borla atak) and all sound similar to the muffler delete. Yes the Camaro sounded amazing but on the trucks I don’t see a big difference.

what muffler delete did you use? is it a DIY version without having to go to exhaust shop?
 
The flapper is only on the '23 model trucks correct?
Those with the '22 never came with that option.
 
I thought they all had the flapper, but I may be wrong. N o reason to leave it in if doing a muffler swap.
I have a ‘22, it has the exhaust flapper, assuming that’s what you are referring to? They are for any AFM/DFM enabled exhaust to regulate back pressure as the cylinders shut on and off I believe…not a mechanic/engineer but that was my understanding.
 
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Thanks guys, I was not aware of what the flapper valve was unil now.
I did a little research... that thing will be coming off when I do a cat-back.
I thought people were referencing the dual mode or active exhaust that the 2023 have.
I see now that it's something completely different.
 
I went ahead and installed a Borla Crate Muffler part number 400843. Removed stock muffler plus flapper and left everything else intact. Start up sounds great as well as when you punch it. Getting some
Highway drone. Any tips to help reduce in cabin noise?
 
I went ahead and installed a Borla Crate Muffler part number 400843. Removed stock muffler plus flapper and left everything else intact. Start up sounds great as well as when you punch it. Getting some
Highway drone. Any tips to help reduce in cabin noise?
Probably not much unless you go with a designed system. Some have added another resonator before the can. You can see how Magnaflow did it on their system in this thread.

 
I went ahead and installed a Borla Crate Muffler part number 400843. Removed stock muffler plus flapper and left everything else intact. Start up sounds great as well as when you punch it. Getting some
Highway drone. Any tips to help reduce in cabin noise?
I had the exact same issue. LOVED the sound but at around 1500-1700 RPM (highway driving) the drone drove me crazy. I pulled it off, sold it, and put a CORSA Cat-Back on her and the cabin was quiet as a mouse and sounded awesome outside the truck. You can also buy a resonator which many stated would help.
 
I went ahead and installed a Borla Crate Muffler part number 400843. Removed stock muffler plus flapper and left everything else intact. Start up sounds great as well as when you punch it. Getting some
Highway drone. Any tips to help reduce in cabin noise?
Install a third resonator between cat and the Borla. I had similar issue.
 

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