I took a more simplistic route to getting some thump to my music by buying a JL Audio Microsub 8.1. Yes it's only a single 8" sub but it hits hard and clean. It also comes in an 8.2 model which has 2 8" subs and they really hit hard. The 8.1 fits neatly in the corner of my trunk and still leaves enough room for 2 golf bags or my t-tops and all my beach gear. Just a suggestion...