Just wanted to give an update on my 2016 Yukon XL 5.3L SLT 4WD (no sunroof, no magnetic ride, and no noise cancellation)
*I believe Denali package with magnetic ride and noise cancellation has less booming as I test drove my friends 2015 Denali XL and it sounded much quieter, but he did have Michelin tires on 20" wheels*
I had low speed booming noise that was bothering to my ears and slight buffeting that would get worse at times and come on and off depending on road surface and tire flat spots (i drive the car few times a week, not every day, sometimes once a week)
I took it to GMC dealer and asked them about new exhaust and dampers but after their inspection they said that service tech added some weight to roof and stated that the noise was mostly gone and therefore got GM to approve to re-glue/re-attach my roof to roof bows under my certified warranty using PIT5318D
I think there is a new procedure where special 2-tube glue mixture is used and it dries quick and forms into a thick compacted soft foam where it will not crack anymore. (because about 10mo ago when I asked Chevy dealer about roof fix they told me that by my VIN# my 2016 is not under the PIT#)
While waiting on parts I also bought a 36sf package of dynamat at my own expense (sound deadening material that i wanted to install myself but didn't get to it) and asked the dealer to install it to the roof before attaching the roof bows to roof. (I offered to install it myself while they have the roof-line down but they went ahead and installed it at no additional cost)
Now the Yukon drives much better and the roof is solid and when you close the door it barely moves and when you tap on it it feels solid. While at the dealer I test drove the new 2018 Yukon XL SLT 5.3L with sunroof and it had 18" wheels and Michelin tires and it did have about the same booming at low speeds, maybe slightly less, but that could have been to car being brand new and sunroof and Michelin tires.
I asked dealer about shocks and bushings and was told mine were good and that there was updated for magnetic ride/higher end models.
There is still booming at slightly rough roads at low speeds but it doesn't hurt my ears anymore as the tone of the sound is not that high as before... (before, because the roof was lose and of thin metal it was acting like an amplifier for the booming and increasing the noise) I still have original Goodyear tires and I can barley hear any buffeting even after the car is parked for a week. I know that Michelin will improve the ride even more.
Few months ago I even thought to downgrade to older Yukon XL and test drove a 2012 Yukon XL SLT and it also had some booming, maybe slightly less but it had way more overall road noise. I was hoping for better improvement but I guess It is pretty normal for GM and many other SUVs/trucks to have some booming and I have heard that only hydraulic body mounts will improve it farther. (I had 2007 Navigator L in past before switching to my 2016 Yukon XL and it had less booming and I believe it has hydraulic body mounts and also independent rear suspension, but wind/tire noise was worse on it)
I plan to eventually switch to Michelin tires and add some dynamat to floor under carpet just where the carpet comes off easily without taking too much apart, (i read it on another forum that someone did that fairly quick as most of the floor is easily accessed by just pulling the carpet off without disassembling anything, and that it improved on tire slap noise and overall noise)
Hope that this helps others, and please share if any other repairs helped improve the ride.