I've been having some problems with my McIntosh sub causing rattle. My music didn't have to be up very loud in order for it to be the case, so I went to a couple of audio shops in search of a new sub.
Long story short, I purchased some Stinger Roadkill (Dynamat alternative) and put it on my parcel shelf. I also glued my McIntosh sub as it had cracks (see the pics) and it seems to be fine now.
You can see the brown, cracked area. I wiped the cone clean and glued it together.
Insulation coverage - around 3/4 of a sheet used.
I also had some additional Roadkill, so I put it in my front doors. Used 2 sheets overall for the parcel shelf and front doors.
Insulation coverage, used a bit more than show in the pictures. Used roughly 1 and 1/4 sheets.