hispls 5,000+ posts
CarAudio.com Veteran
Man I wish i had four 9500's in my scion
You do not have enough space for 4 15s in that car any way you slice it. As you see already you're struggling to fit 2.
I don't think those 2x6s on the sides of the box are helping at all. Lose those and looking at the last pic it seems you might be able to slide the box about 8" further to the front just to test how leaving a bit more open by the port side will effect things. Those side pockets look like good spots to tuck amps if you can fit them there.