Rook126

If you haven't already seen this, here's an old post with some opinions for you.

Here's a pic after applying the seam sealer. The sealer was glossy black. Blue painters tape was used to prevent any spillover onto the outside of the rear glass. Also, notice the circular rings of 3M windshield butyl tape I place around every bolt hole for the spoiler. I didn't trust the original foam washers that were deformed under compression when the spoiler was bolted from the factory. If you are not aware already, this is a common problem that many have already posted about on this forum.

Taken from the outside looking down with the spoiler removed.

Here's one of two fractures I found on the brittle plastic frame at the top edge of the rear glass. Repaired it back in December with a tube of 3M Urethane Seam Sealer, 08367, Black Color and it never leaked again. Just run a bead of this self leveling sealer alone the entire length of the plastic frame so water will never settle in the channel.

I'm steering toward a heat shield as CamGTP mentioned. This might not be the source of your noise but it was for my 2020 Sierra.

Do what dram mentioned above and try the rear first. You will notice a big difference in the handling at high and low speeds. I have the Hellwig bar on the rear and stock on the front and I'm still happy the the purchase.

Get the 11mm versions instead of the 6mm which were not very bright when I first tried them. They were too dim to illuminate the interior so I ended up with the 11mm installed. See the link to the Interior Lighting thread above from Bikerjon.

Don't invest too much into the door speakers. The Bose system limits the frequencies to the doors speakers and you'll get mostly mids and muted highs. The 2 way Kickers in my doors sound flat. Same for the rear door speakers but they are even lower in volume than the front doors at the same volume setting. Invest in some larger tweeters for your dash with the right capacitor to give you clear mid/highs. This will balance out that sub output. I'm run a 10" Solo-Baric. When running this set up, I have the radio's bass set at full negative and zero for the mid and treble. No muddy bass but it gets fairly loud inside the cab.

I drive the same year and Denali trim you mentioned. I mainly use a Bluetooth connected iPhone for my music but I also have been using a stubby 128gb SanDisk USB drive that is left in the USB port under the center console lid. Formatted in FAT32. Amazon still sells it for $16. SanDisk 128GB Ultra Fit USB 3.1 Flash Drive - SDCZ430-128G-G46 There is also a 256 and 512 but I don't know if they will work. You can rename your USB drive and that is what will show up on your screen as a music source. I have noticed it spending 30 seconds to a minute indexing all of the files after you first plug it in and power the radio. Music from the drive will play while it is indexing but you just can't navigate to other songs until it is done. Note that the larger drives with more files will likely take more time to index. iTunes already organizes all of my music files into folders named after the artists. I just went to the folder where iTunes stores all of the media and copied every artist folder onto my SanDisk USB. I haven't experimented with creating playlist so I'm not sure how that is done but the option is available on the touchscreen. Music is sorted by song, artists, genre, album, etc. Play anything you want or just shuffle it all. Song information displays just as it does while play from your phone and the album art displays on the screen if you have that too.

Could your lugs be "Splined" requiring this FUEL Splined Socket Key? Only $5 in this link. https://fueloffroadutv.com/products/spline-key Here's another image from this site. https://agileoffroad.com/product/agile-splined-lug-nut-key/

Here's a thread that might give you some additional information.

I resolved this noise a couple months ago but my post did not get much attention. Here is how I made it go away forever.

For those who are still having this heat shield noise issue, I wanted to let you know that I have not had the noise for the last couple months so I believe it is now resolved on my vehicle.

As with many of us, this buzzing vibration noise has been eluding me for months. It sounds like a heat shield or thin metallic sound just as some of you have described. I typically only hear it randomly at very low speeds and rpm such as when I am turning into a parking space or reversing slowly. I'm certain it still happens at higher speeds but I don't really notice it because of wind/road noise or the music being turned up. I've seen the other posts mentioning the heat shield at the spare tire and leaf springs but this was not my case. I went back under the my 2020 Sierra today and combed over it inch by inch, plucking and hammering around. The heat shield at my spare tire seemed fine and didn't have any clearance issues with my GM performance exhaust pipes. I made it up to the fuel tank and finally replicated the buzzing sound when I hit the plastic tank. I discovered the buzzing vibration sound was coming from the fuel tank heat shield on the driveshaft side. I reached up to the top of the heat shield and bent it at the top slightly away from the tank and the noise is gone whenever I hit the tank. I initially flexed it too far and popped out one of the plastic retainer clips. It was easy to reseat the clip. I haven't been able to replicate the noise for now but only time will tell. Listen to the video clip to determine if your noise is similar. I have not come across a post about the fuel tank heat shield yet so I hope this helps some of you out. buzz.mp4

The Hellwig rear sway bar is expensive but well worth it to me on my 2020 CarbonPro Denali (non-AT4). It was my best upgrade/mod and I immediately noticed the improvement in handling and lack of lean during corners and quick lane changes. I still have a stock front sway bar that works just fine in conjunction with the Hellwig rear. Hellwig makes are rear bar specifically for the AT4 with the higher suspension than mine. Here's my previous post on the install if you haven't come across it already. '

Sorry for the late response JIGGZZ. I haven't been checking my notification lately. Here's an older post where I tapped into the Bose sub wires for my low frequency signal to my aftermarket amp.

I have a Sierra 1500. I initially tried the popular aftermarket rubberized stubby you find on Amazon. It performed fine and required a thread adapter which was included. I only kept it on for a few months because it got tired of noticing it all the time. Although it was short, the thickness of it stood out to me. Just about all of my front seat passengers would ask, "Was that always there?", referring to the "covert-stealthy stubby antenna. I ended up replacing it with a shorter version of the factory antenna. It is 7 inches tall and does not require a thread adapter. Looks stock but a lot shorter. Performance of this antenna seems to be the same as the stock one. All the same stations come in fine. I found it at theantennasource.com. Free shipping was quicker than I expected. https://www.theantennasource.com/GMC/SIERRAPICKUP/Sierra2020-1500.html#1A They also have 9, 12, 15, 21, 24 and 27 inch versions in black. Other sizes come in stainless.

There's a different model (7782) for the HD trucks and it is a lot more expensive for that rear sway bar.

The sway bar is not required on any vehicles. It's up to your preference on how it feels and handles with your setup. Hellwig's website shows that they have a rear sway bar that will support lifts from 2"-4". REAR SWAY BAR KIT2019-2020 GM SILVERADO/SIERRA PICKUP W/ 2-4" LIFT Part Number: 7844 You may have to contact them to see if they have any additional hardware that supports the 6" lift.

I don't think a dealer will touch it because it is not an accessory provided by GM or dealerships. I installed it myself and I don't recall having to take anything apart during the install. You just mount the hardware to the vehicle in certain locations. So far I can't see any reason a sway bar could be detrimental to the ARC or would void your warranty. GM chose not to include a rear sway bar on their 1500 trucks (probably to save cost) but I notice that all of the recent Tahoes come with rear sway bars. I had a 2017 and a 2020 Tahoe with factory rear sway bars and both of them handled corners with a lot less sway much better than my brand new 2020 Sierra Denali before I added the Hellwig to the rear.

Yes, the rear sway bar prevents a lot of that front end dip and body roll around the ramps and it makes it seem like all four tires are planted more equally. I only added the rear Hellwig and there's a factory bar already on the front. Traction still feels balanced, no noticeable oversteer or understeer around a quick corner under acceleration.

If you are satisfied with your existing amount of sway, you may not want an aftermarket sway bar. Your driving style may not require it either. My truck has the ARC and Max Tow Package. My ride comfort didn’t change and it doesn’t seem to compromise the ARC system at all. I feel the rear sway bar made an improvement that was most noticeable for the investment. It added more confidence in cornering and evasive maneuvers if necessary. On and off ramps are easier at normal speeds because there is less leaning going on. If you do decide to go with a sway bar, take note that there are two different kits. One for the standard height trucks and another for the higher AT4s with the 2” lift.

Although this sway bar was a litter pricier than most, it was the best upgrade I have done so far and well worth the money. You will notice the improvement immediately and enjoy driving your truck even more. I recall being a little disappointed with the amount body roll it had when I first bought my truck but now it corners so much better. Enjoy your upgrade.

I think I experienced the same issues you had but just didn't mention it. Sorry about that. I had the leftover black washers too. Glad you got it all figured out and are enjoying the cornering with confidence. Great job!

As you can see from the image, I installed mine using the 3rd hole from each end of the bar. This is the stiffest setting and there are no drawbacks or regrets. The ride and suspension seem just fine. I have inspected everything a few times since the install and have not had to re-tighten anything. Feel free to ask if you have any questions on it. Good luck with you install.