I know this is an old thread, I just searched through a bunch to find it and add to it...

I had some nasty rattling in my doors... found that the plastic lining was torn in several places... tore it all out and re placed it with 6mil plastic sheating from lowes... doing some re-modeling and had some around anyway... I also decided to throw some r-13 fiberglass insulation inbetween the door panel and the plastic, yeah it makes putting the panel back on a bit harder, but the result was surprising...

Not only do my speakers sound louder, the bass response is much better, and the road noise was drastically reduced. now Dynamat might indeed be a better choice, but this stuff was free, I already had it lying around in my shed, and it made a big difference... apparently the plastic does serve a purpose... it separates the front and rear airspace of the speaker, and the result is better performance, and the fiber glass helped with the road noise...

I was also told that something else that will also improve sound quality is if the metal structure of the speaker does not touch the door, in otherwords put something in between to isolate the vibartions and stop them from transferring through the metal...

BTW I have pioneer 6-3/4 inch speakers in the doors.

 

that sounds like a cool idea!

 

Yeah all I have to do now is figure out how to keep the metal rods for the door handles from rattling... my pioneer speakers sound good though...
I am still probably going to have dynamat put in eventually. But I might get a newer civic next year, so I'm trying not to put too much into this one...

The fiber glass does make a noticable difference, do a before and after... only thing that sucks is you can't get rid of wind noise from poor weather stripping...