I can post pictures of mine in just a little bit. If optimal sound is what you're going for, I wouldn't actually recommend mounting the speakers behind the seat. All you're doing is putting all of that sound right into the back of your seat. Your seat will absorb a lot of the higher sound frequencies. Although I haven't done it myself, I would buy the speaker kit that mounts the speakers at the back of the hatch. That way, the sound has a clearer and more open path to travel. This should preserve the sound frequencies a little better and allow you to hear it with a little more clarity (as the speakers would also be mounted a little higher than the tucked away, behind the seat position). That's just my two cents.
Now With Pics:
These are 6" Rounds.