Apparently, the factory 6x9's in my van's doors provided a decent amount of bass. Now, with the JBLs installed the mids and highs sound my more crisp and clear, but I've lost a lot of bass. I'm thinking now about replacing the 6x9s in the rear panels with something that has a better bass response. Should I just go with a normal 2-way coaxial, or some sort of 6x9 subwoofer? Or, if you have any other ideas, I'd love to hear them.