One thing I would do differently (maybe) is use only one instead of two. The trunk of my Acura TL (12.5 cubes) is seemingly not large enough for the pair, causing me to have to cut 50hz quite a bit and boost the low end. Removing all carpet (adding trunk volume) has made them quick, tight, all of the above again and I'm currently using no EQ on them. Obviously I can't go without trunk carpet forever.

They do so well in the upper frequencies that even with 9" midbasses I always want to let the 15s play up higher than normal.