We gotta keep in context with the user. Ok, he's been here a month, 26 posts, probably his first system; he doesn't know what to expect. Probably just that signature bump. We can guess like most newcomers, he'll be running sealed in an unoptimized install with a healthy level of clipping. In this situation, the sub does make quite a difference.
Sure, why not. Incriminator Audio 187. Rated 300wrms, I've pushed 7 times that to one DD off an MTX 1501D. They put up high numbers; they are tough as nails; work well sealed; sound good; and only cost ~$100 + shipping each. =)