I am still in the process of following up with work I have already done on the runner over the summer/fall.
Sound Deadening:
This might be a loaded subject, and some of this approach has gotten popular recently. Yet, the performance and goals can be questionable. Since I removed some of the OEM sound deadening (Constrained-Layer Dampening), I thought it best to replace. Plus, this is no fancy LC to begin with, and is built like a basic tin can. So, it seemed like a classic case of "while I am in there".
I found a pretty good website/company that covers this material/topic.
https://resonixsoundsolutions.com/r...-deadening-material-independent-testing-data/
They do a great job formally testing many of the popular products in the market. Of course theirs is the best performer, but it is also the most expensive..by a long shot. My take away is there their is a much more approachable option that still had good performance. So I went with the Amazon Basics Car Sound Deadener.
https://www.amazon.com/gp/product/B07XJ5MVQ8/ref=ppx_od_dt_b_asin_title_s01?ie=UTF8&th=1
Not only is Amazon's version like a tenth of the price to begin with, but they are on sale often. I got the 34-piece kit for $40.
Its important to understand that constrained-layer dampening is NOT soundproofing. The goal is not to achieve full coverage on the floor to stop sound from entering the cabin. That is not how it works, or the mechanical function that is occurring. That is why many folks talk about 25% - 75% coverage (not 100%). The simple way to put it, it manages and reduces a surfaces ability to resonate by dissipating energy through heat in the viscoelastic layer. To me this material is for "sound conditioning" not "soundproofing". (FWIW, I have history with soundproofing in other applications)
Now, for my project, it was not necessary to have a well controlled cabin space. Plus, I plan to have a softopper which will be inherently noisier in general then a traditional SUV anyway. But, "while I am in there".