I am having the same issue, I have a 2020 denali with the 6.2, 6'7 bed and had a local shop remove the muffler and flapper and put in a super 10. I left the resonators in as I don't want the drone either, I pull a trailer quite often. The super 10 had drone when cruising, in 9 and 10 under very little load. It had a crazy drone pulling a trailer. Went back and had them do a super 40, as this was less aggressive. Sounds very close to the super 10, has less drone, but still more than what I'd consider comfortable especially if driving more than an hour.
I'm not sure what to do now, I'm half tempted to have the stock muffler put back in, or try a borla cat back and hope for no drone. I pull a trailer too often, and on longer trips so trying to get the sound without the drone.