Just did. Using the same app for before and after.

When idle and the car is warm:

Before: 23-28 DB
After: 18-25 DB

As you can see the DB difference is not significant, but you can hear/feel that the car is isolated and the exhaust sound is toned down/muted.

Anyhow, I'm happy with the results and would recommend to anyone to isolate their trunk if they have noise issues. I would suggest cheaper solution than Dynamat, if you can find one. :icon17:

How about a road noise test?

Too late for the before number.

As cooltoy said, it's too late for that. However, I've applied dynamat only where most of the noise is coming from - trunk of the car. Road noise didn't bother me before, but I'm sure if you want to significantly reduce it, you'll have to take off the carpet, door panels, trunk panels and apply some form of isolation. As I said before, my exhaust noise in the car is more tamed right now.
Keep in mind I have stock headers, HFC, and the full Tomei exhaust. I can't wait to see what my car will sound with the Z1 headers and TPs.

3-5dB difference is very noticeable and significant. good job :tup:

Cranzy my understanding from researching this stuff is that it is mainly for vibration and as such does not need to fully cover every panel are you able to comment on this. I am also under the impression that a proper sound insulation rubber mat would cut down sound more than what you have achieved?

I'm under the impression dynamat isolates in such way that less noise can pass in or out through it. It is usually used for better sound performance inside the car, but it also cuts down road noise and such.

I haven't tried the rubber mat because I didn't have the energy/patience to put another layer on top of what I did. I would assume it will give you better isolation though since the factory OEM mat doesn't go past the strut bar. ;)