I think I may be that dude. Here is my modz page. https://www.subaruforester.org/threads/my-2019-subaru-forester-sport-let-the-modz-begin.792005/
That post is one mans opinion. There are a bunch of knuckheads on that site. I read a bit of the postings and see nothing convincing.
I have invested a ton of time and money into applying sound deadening materials and mats in this vehicle. It has made huge improvements on a quieter ride and more important improved audio sound quality. Where I notice the biggest difference is in three places.
1. Tap on any door panel and it sounds dull. There is no metal ping or noise accociated with vibrations in the metal.
2. Improved sound quality. The 6x9s in the door move a lot of air and this will vibrate the untreated metal in the door. This creates unwanted noise and rattles that competes with the speaker iteself, especially at higher volumes.
3. Many cars with high end stereos sound great when you sit in it with the windows up. But, on the outside these car will rattle like hell. Treating the metal panels (and license plate) will stop these vibrations. My car sounds as good on the outside as it does on the inside. It takes work to make this happen. And I feel it is critically important.
I am not sure what proof he needs. Sound deadening material does more than quiet the ride. It removes and absorbs metal vibrations. Despite all the material I added, I still have one nuciance spot that tends to rattle on deep bass notes. That is the panel with the gas tank filler. This panel is hard to treat because there are so many points of rattle.
If this stuff did not work, then why does every winning car audio vehicle use it?! Also he make a point that if you want a uite car, then buy one. The $80k cars he references are in fact using tons of sound deadending materials, mats and panels which isolate the road and motor noise. Just because the cars do not use the traditional butyl sound deadening material does not mean it has no treatment at all.
My opinion is to add deadening materials. There are many brands available. They all work. Some work a little better that others, but not by a huge margin. Choose what you can afford. I like Dynamat and found a good deal on the Dynamat Extreme Bulk Pack on ebay for about $160. That was a good value to me and the material is easy to apply. I aalso have some Stinger mat and something I bought from Best Buy in the doors. So, my car has several brands, but all have similar properties. Once I started getting serious with the application I used Dynamat because I bought the huge Bulk Pack.
As for best areas to apply, the Dynamat website has some good suggestions on which areas to treat in a logical order. If you do not plan to treat the whole car then I suggest you treat all four doors. Then play a heavy bass song and locate rattles by walking around the outside of the car. As you find those spots, treat those areas. Keep doing this until you feel satisfied. Again this approach is to improve sound quality of the audio system more than to quiet the ride.
I like to listen to loud music, when I do, I don't hear the road noise even before I deadened the panels.
For me, sound deadening material improves the overall sound quality as much as it makes for a quieter ride.
The first post on page 10 has my recommended list of areas that i thought made the biggest difference.
Below is the short list. There is a full description in my blog.
Here is my recommended short-list of preferences for audio (first priority) and road noise (second priority)
Cargo area with fenders
Again, Dynamat has a good description of this as well. Adding material to the hood did not do that much to quiet the car or improve the sound quality. A lot of work and cost with that treatment, and I would suggest treating other areas before that one.
Visit this page, Dynamat Xtreme Information
. The download gives you there suggested order of adding the materials.