Carl,
I read a number of posts, on s2ki.com, where several of the guys had used this product, and had very good results with reducing road and exhaust noise, from intruding into the passenger compartment.
In fact, I have added this to my (already too long) list of projects to undertake.
I tried searching the s2ki forum to find the thread, but it wasn't coming up in the short amount of time I had to look. I will continue to try to find that thread...it was encouraging.