
Originally Posted by
jhnkvn
Hop on to another Altis and notice if the NVH levels are the same. If it isn't, then you might have a "hole" where outside noise comes through the cabin.
Unfortunately, insulation isn't just a one-trick pony and it's expensive as an endeavor. Best to simply "go up a class" if you're seeking better NVH levels because NVH control starts at the very chassis and how the vehicle is constructed.
A sound deadener's primary purpose isn't to deaden sound really. It's to lower a panel's resonant frequency (for those into car audio) so it rattles at a lower and less offensive frequency. The magic in NVH insulation is that you need to create a "bubble" to isolate the cabin from the outside world. MLV deadeners may marginally help by plugging in "holes" and absorbing a certain amount of noise, but don't expect drastic changes. But in the event you really want to go this route, you deaden three key areas: the firewall, the floor, and the tire walls.