You have 4" in the doors and in the rear you have 5 1/4" according to the sounddomain web site. I'd spend the money on a nice set of 3 way components for the front. Using a 4" midrange in the door spot. And then build kickpods for the 6 1/2" midbass and tweeter. I wouldn't put anything in the rear and just use the holes there to let the bass come in from the trunk if you plan on running some subs.