it cuts down on it some, it more absorbs vibrations that blocks out sound. no rattling and everything is much crisper. i added 10ft2 of dynamat on the hatch today, still need to do behind the taillights; but im waiting til i change my tail light gaskets. anyway, the extra layer on the hatch helped a good bit with the rattling in the back, but the windows and door panels still are about to fall off. projects for other days...