To:
Eliminate the rattling and vibrations due to bass and road condition.
Eliminates the road and ambient noise in the car.
Make the cabin more quieter to hear the audio to its fullest.
The cabin being more quiter , you can hear audio system at low volume easily which is good for life of speakers.
In short for an SQ or SPL systems this is one of the major upgrades and is commonly practiced throughout the world.
Sent from my iPhone using Tapatalk