I added some 6X9's, man it's kind of a pain in the butt to cut out that cardboard back there, even with airtools, I don't know why they made that stuff to hard. I added a small mtx amp for them, it worked out great because I can not set the level of them to make sure it still sounds semi balanced. I almost didn't even need a subwoofer after this install, but hey, I alredy bought the sub and amp.
Eamonn