Never heard of anyone wanting to make their car quiter but that sound dampener is pretty good.
If you read the later posts by "Fuelboss", for him to say what he does is quite something. He is over here in UK & created a few websites about the problems on the early MK7 Golf Sachs rear dampers. He also had a few problems with noise from other MK7.5 Golfs & finally has a MK7.5GTI which's he has done loads of sound deadening to etc. As a long shot he tried the damper, not thinking it would do much & was very skeptical..but he's been very surprised!!
When VAG first designed the multilink rear for 2003 MK5 Golf platform (A5 PQ35) it must have found that the subframe had a natural resonance which amplified any noise transmitted through the subframe from the suspension. The engineers then created a "harmonic damper" to cancel out these frequencies in the subframe, by drilling two holes in the subframe & mounting the "balance weight". This part was then given a code starting 1K0 which is the code for the new parts on the MK5 Golf. The part was not put into mass production & first appeared on the MQB platform Audi A3 saloon.
So if all A5 (PQ35) & MQB rear subframes have the two holes drilled for it why was it not fitted until 2013 on the Audi A3??...Bean counters decided not to fit for cheapness on the other cars & the noise was too great on that specific A3 bodyshell for the "premium image" so they fitted it??