So I ordered their 40SQ Ft kit to start with and we'll see how far I get.
I looked at the Dynamat Extreme door kit which is 12 SQ. FT per box and they said one box is good for doing the interior and exterior of a single door so I'm thinking this will b enough.
I should get the Damplifier sometime this week and hopefully install it this weekend if I get my trim removal tools from amazon. (I'm sure I don't actually need them, but I'm terrified of scratching my wrx)
I'll also be installing the Kenwood KSC-SW10 under the seat while I'm at it.