Datapoint, first attempt! Summary: Big improvement!
I was able to reduce boominess thanks to @ilovecoffee
's idea of the vinyl tubing stent (how I describe it to my friends) in the rear hatch seal. That's all I've done; nothing else. Huge reduction in boominess and car is that much better to drive. 2023 MYLR with 19" gemini wheels (Continental tires) - I registered an account here just to share my experience.
Already had a 2019 Model 3 base which we've put 43,000 miles on it. Added this 2023 Model Y LR to our stable in January. It has 1100 miles on the odometer as of today. Longest trip taken in it to date is a 60 mile (each way) trip from orange county to LAX. Otherwise just weekend city driving within a 30-40 miles radius. Every time, leaving our driveway all the way to the freeway, there was always something bugging only me. I described it as "bassy" and "cavernous" and "rumbley" to myself, but nobody else in the family mentioned a thing. I figured I would get used to it or it was in my mind. Did a few searches and finally came across this forum. 3 years, 64 pages, wow! First I tried the 4 hatch stop adjustments, I couldn't tell with absolute certainty if there was any substantial improvement. So 2 days ago I decided to go all-in. Bought vinyl tubing (20 foot coil, $7) and "specialist silicone" wd-40 spray ($9) from Lowes. In the end, it was 3/8" OD (Outer Diameter) that worked best for me. I had first installed the smaller 5/16" OD, but the stent was just rolling around inside the rubber seal and while I think it improved things a little, I wouldn't swear on it. So I removed the 5/16" OD, and up-sized the stent to 3/8" OD which filled the rubber seal better. I then re-adjusted the hatch stops, and I think this is where I'm going to leave things for a while because I'm very satisfied. The rumble is reduced so much that I already saved a D-Shape weather strip EPDM in my amazon cart for later - Now I started noticing wind noise and I need to take it easy. For the record, I did zero noise abatement on our 2019 Model 3, and I enjoy driving the Model 3 a little more. The Model Y is good for passenger space and height. (They're both good cars, bront!)
Question for @ilovecoffee
: I actually ordered butyl and started taking apart the passenger side quarter panels. But when I got in there, it already looks like there is a bunch of sound deadening material applied. So I took some photos and put everything back without making any changes. Do you think Tesla has since added extra sound deadening material? Is it something new on my 2023 Model Y that they didn't have on your earlier version? I'm attaching some photos:
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Zoomed out to give a sense of space. There's already a lot of sound stopping material on the cabin-facing panels.
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There seemed to already be a big fit-to-shape sound deadener installed here. Upon seeing this, I decided to stop, take pics, and put everything back. Did Tesla add this new?
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A different angle, with flash light shining on one spot with bare coper painted metal. Tapping there produced a "metallic" sound here, but I didn't make any changes.