I'd also like to add that I started by trying to get my frequency response as flat as possible by just using clever crossover point and slopes and gain setting. That way non of my parametric eq bands were waisted on crossover gaps or driver capabilities. I wanted all if the bi-quad filters to be directed towards frequency response issues related to the acoustic space. It worked out quite well!
Also, everyone has been bustin my chops about a midbass needing the polarity reversed. Every time I mention a lack of impact that the response I get. Well a few people gave me the advice of raising my crossover point to clean up my midbass and let the subs do some of the work. Well this worked like a charm and I managed to retain my upfront bass by trying different slopes. I'm currently using 18db BW filters on my L8's HP and a 12db BW on the LP. My mids are HP'ed with a 24db LR filter.
And as it turns out my entire stage was inside out! What I thought was a decent image was messy and wide. I reversed polarity on the passenger side full range and everything tightened up. It's like my left and right are earphones and the car is my head. Saying my stage was inside out is the best way I can put it. I'm sure you guys know what I'm talking about.
Sent from my Springfield XD with love!