I was about to dynamat my floors but I'm guessing you wouldn't recommend it Ben? I've got brand new normal underlay to put in as I had a fuel leak that ruined my original rubber topped stuff and some of the factory bitumen deadening stuff.
Dynamat is very good and a lot more efficient than the factory stuff as it is much lighter.
What you need to remember is that it's an anti-drum pad. You only need enough to take the drum out of the panel you are applying it to.
Here is one I did with OE spec pads
You don't need any more than that and it certainly doesn't need to go on the bulkhead or toe board in my opinion.
If you want to put any in the boot, just put a square or round pad in the centre of the wheel well and this is enough. Any more is just a waste of time and money.
The only other places to put them really is inside the quarter panels and inside the door skins but again, one pad is enough to stiffen things up and take out the drum.
Cheers
Ben