I've got 2 JL 12W3's in a sealed box premade by Tweeter powered by a JL 500/1. Head unit is an Alpine 7878. I've had it for a few years now, and I've never thought the bass was deep/loud enough. I've got no room for 15's or anything bigger than 2 12's. I like r&b and rap. Would I be better off going w/ a ported box or a bandpass box? If ported is the answer, can I "convert" the box or do I need a new one? Thx.