I drive a 2003 Hyunda Tiburon GT. I've heard from one person that 18" subs don't do so well in smaller cars. I was looking for some more input on this subject. I have a 15" RD Sonance currently that does just fine, but I've been looking into some Fi Subs and I'm considering the possibility of maybe a 15" or 18" Q or bl. Anyone have any suggestions on a sub and a size? LOL. Thanks everyone! Corey