I would only use the asphalt based stuff on the floor.
All mat products only need to be used in specific resonance prone areas and to seal things up like access holes in some places so a great deal of it is not needed.
None of them are great thermal products though some claim to be they are simply to dense and heat soak quickly.
Some have slick advertising and sound quite convincing, I was the first in the industry to offer a lower cost solution to the big name brands many years ago and have seen all sorts of marketing come along to get you to pay more than needed for some great products just overly hyped and over priced. The good thing with them is at least you are getting real deadening as there are a lot of scammers selling simple roofing products and calling it deadening, it does work to a degree but not as well and not going to hold up over time.
Use whatever brand you prefer but make sure it is the real deal, use just enough to get the job done, as in all things middle of the price range is almost always the best value.
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Besides Ensolite, which I was the first to introduce it to the automotive sound deadening realm and chose not to rename it and mark it up even higher, is still the absolute best foam product I have ever found. I was developed for the space program, thermal and acoustical properties, fire retardant, low weight, low cost, used, and it was chosen along with my mat product for the International Space Station Training Facility.
I received a rather large order from an engineering firm and called to inquire what it was purchased for as was quite curious and also might have some helpful info on getting the best use out of it. When they told me they checked into all the different products they chose mine because of quality, value and reputation, I was obviously quite flattered to say the least
I offered to donate it to the cause but they could not accept it that way, I offered half price, they could not accept that either so the best I could do was wholesale.
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The ST is a bit tricky in some areas and a bit different in others like how the doors are inside, the biggest issue is the hatch as in all open cars, vans, etc....some of the egg crate acoustical foam can help a great deal as mentioned as this is a rather noise car and some of that is caused by stiffer suspension bushings which is harder to deal with.
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Again, this is not an advertisement though it could sound like one, just telling it like it is from one that has helped tens of thousands around the world do this the right way and always the lowest cost way while skipping all the advertising hype some tend to use.
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I like many others love a great sounding exhaust, intake as well, just not drone and not to loud, louder when getting on it is great, mellower the rest of the time is best for longer drives especially.
Have a great day
Rick
