Noise, vibration, harshness (NVH) is a science unto itself. There is only so much you can do with older unibody cars that were not originally designed with NVH in mind, but you can make significant reductions usually with some added weight using dampers and isolators. I also think stricter tolerance balancing on all rotating assemblies (engines, flywheels, and driveshafts) can also provide benefits. As was mentioned if moisture gets in between the metal and the material you know what happens. I like Second Skin Audio products, they are based in Tucson, AZ--go Wildcats; and their products are made in the USA.