so i decided to rip out my rear interior and put in some sound deadner. Where I live in Canada they use sand in the winter because its too cold for salt to work properly, and it is really loud and annoying when using my bluetooth or driving for 4 hours with sand rocking in and out of my wheel wells.

The rear seats and spare tire was removed just for fuel consumption testing. In the city it was improved! I got 9.1L/100Km (25.5mpg)

As for the road noise, its decreased quite a bit but when driving above 80Km/h, wind noise is still present. (my next attempt soon)
Thought I would share some pictures.

 

i think the sb comes with sound proofing in the windows with one of the add-on packages, but it doesn't seem to be enough.

i'm starting to notices the rattle in the rear from gravel and such too. i like what you've done and might have to follow suit.. what material did you use to insulate the surfaces?

 

I'm not sure of the name of the product I just asked the local home depot for cheap sound deadener and he gave me this. It looks familiar to rug cusion.

Never knew there was sound proof with some of the add ons. Well maybe here in canada we dont have that package.

Oh yea if you are going to remove your interior let me give you a tip. Remove your seat cusions FIRST! i had a hell of a time doing it backwards. But removing the entire interior will take you about an hour the first time - and maybe 15 minutes next time.