As I begin my adventure in the SQ lanes, I have been doing a lot of research and studying. My general synopsis is, for SPL, in a vehicle, we want the most reflective material possible, such a concrete, or marble, so that there is no loss in energy. Obviously this is not practical, but in this example, it will work. Ok, and for SQ, we want the total opposite, we want complete absorption so that none of the higher frequencies reflect, which can cause interference, overlap, and many other issues. From what I've seen, things such as egg carts, foam, or MLV would be the fix. So what I am asking, what would be the best and most particle material to use in the vehicle for sound quality purposes? Particularly for the dashboard area to prevent reflection from the windshield. From what I've been told, one of the major goals is to get the sound stage to be perceived as front and center, (pointing at the center dash). But once you get the sound up there, there still may be some issues that needed to be ironed out due to sounds reflecting from the windshield. So I guess I'm asking what would be the best dampening material to address said issue? And again, this is all round 1 for me, so if my thinking thus far is flawed, please advise. As a side note, I've noticed the difference first hand. I was giving an demo to a good friend of mine, and he pointed out that I have too much reflection from the dashboard area. We placed a few of my heavy T-shirt/clothing on the dashboard, which is also made out of plastic, which is very reflective, and I immediately heard a sound difference. That sound difference, can anybody explain to me exactly what is going on here? Like, the science behind it or a good description. I was taking a look at this particular site, under "absorption". http://whealy.com/acoustics/behaviour.html