IMHO......It makes ALL the difference.
I "Dynamatted' the Sh*t out of my car when it was built.
Every surface inside, and UNDER the car...inside door panels.....and double thickness in some places( Floor panels etc.)
Turns Aluminium panels from drums into solid surfaces.
When you knock on every panel,and surface, it sounds like you're knocking on hard wood.
When I shut my doors, I recon they sound like a REAL car door shutting....not that usual hollow sound the Cobras often make.
Love the stuff.
Somewhere under there , there's about 30 kg of dynamat...
Cheers,
Warren