I may be late to the party here, but I had 1 Alpine Type R 10" (and for a while I had 2 of them actually). Even 1 was fantastic for rock. I had it in a sealed box with ~1 cubic foot of air space. I highly recommend.
sealed sound better all around IMO but he's right, ported boxes generally make the bass sound good for rap and sealed sound real good with rock, regardless of the sub.
BTW, Rockford still makes subs if you were curious. Not to bad for the price...
Even though this was necro bumped, the right subwoofer for ANY genre of music is more about building the enclosure to meet the parameters of the subwoofer itself and the environment that it is installed in. The automotive environment has a peak transfer function where even if the subwoofer was built to play flat outside of the car, it will be skewed by the smaller cabin space thereby augmenting the output response. I've seen peaks as high as the 70 Hz range from an otherwise flattish enclosure and as low as the 20 Hz range in bigger SUVs.
Also, this applies not just to SPL but also to a good Sound Quality install too. There are so many theories on how to get this right, and it usually boils down to luck.
