I added sound dampening material to my '13 EX today. I've read about the '13's upgraded sound dampening, which is shown in the first picture. The little black strips are similar to my aftermarket sound dampening but I still decided to add more.
Unmodified:
After installation:
Also put a bit on the trunk lid to create a nice "thud" when you shut the trunk.
I will be adding the material to the doors after my new speakers come in and hopefully the floor if I'm feeling adventurous next Saturday. The purpose of this material is mostly for road noise. I don't play my music loud enough or with enough bass to hear rattling or anything like that.