Why the hell would you want more sound coming from the back?! Lol!
I'm surprised you haven't suggested a pair of boot mounted 6x9's for some of these upgrades...
Crenninger - I suggest you go to a Professional Car Audio establishment & get some professional advice from people who specialise in CAR AUDIO.
You will be humoured as to how much their advice contradicts what so many 'internet experts' advise.