subterFUSE

Most impressive.



Not sure, but it wasn't too much. Maybe 40-80 lbs of dampening?
It's certainly not enough that I have noticed any drop in acceleration.



Very carefully.


My audio installer did all the work. I don't think it's all that difficult.
Just avoid turning the car on while the seats are out, or else you will get the Airbag light to illuminate until you clear the faults via VCDS or the dealership.

subterFUSE

There are 3 components to dampening properly:

1. Constrained Layer Dampener (CLD)

2. Closed Cell Foam (CCF)

3. Mass Loaded Vinyl (MLV)



You need all three of these to make a difference in road noise.

The CLD is the first step. This is the typical car audio dampener, often called "Dynamat"... named for a popular company that produces the stuff. CLD is basically a layer of asphalt with a sticky side. You can flex the material and the sticky side will adhere to metal surfaces. CLD should be applied to metal surfaces to stop them from resonating.

MLV is the top layer that is responsible for stopping the transmission of sound.


CCF is used in between the CLD and MLV to "float" the MLV layer. If the MLV touches the CLD layer, then sound energy will transmit through them. But if there is an airspace between the CLD and MLV, the sound doesn't transmit very well. The CCF gives you that important airspace.



This website explains everything in painstaking detail.

Sound Deadener Showdown

I think they also sell dampening products.



There is a product called "Luxury Liner Pro" which you can purchase from Amazon. Luxury Liner Pro is a MLV and CCF combination. You get the foam and MLV in a single product, which really makes life easier... especially in door applications.


Just be careful about which type of MLV you purchase. Depending on the vinyl used, it can smell very strange. When my installer opened my box of MLV he said it was really stinky. So he left it outside for a day and it aired out and lost the odor.

Luxury Liner Pro is known to not have any odor. We used Luxury Liner Pro in my doors and on the rear parcel shelf. I've noticed no smell at all.



FYI - We used 2 layers of foam and MLV in my car. Each layer usually nets about 10 dB reduction in sound. So my 20 dB reduction was the result of 2 layers.



Lastly, don't get too excited thinking your cabin will be silent. It won't.
I still have road noise, and some tire hum depending on the road surface.
But it definitely is MUCH more quiet now than it was.