Hey Tag,
I my past experience, I personally have felt that 4 - 8" subs are much better and less "BOOMY" for tighter bass music, like classic rock.
Can you add 4 - 8" systems in or am I the only rocker?
I just hate when the car vibrates and the bass is muddy, maybe all my years of drum playing makes me long for a tight thud!
But I am in for a whole set like that. 2 boxes, one on each side, an amp to mount under the rear deck and speakers!