is it easy to self-install a subwoofer? I have a JBL SB400 at home and ok sakin yung bass ng subwoofer nya. I wonder what would be the equivalent if I were to install one in a car? Not necessarily loud and battery draining, just enough to have that "gapang" bass even at low volumes. To add, I do not want big boxes as we need the trunk space as well. Shall I consider an underseat sub? Thanks.