Just my opinion, but I think fiberglass the way to go. I just put a sub in my Reno and made a fiberglass enclosure; it sounds great and I still have a usable space in the hatch. I've seen similar installs in cars with regular trunks; it ends up looking really clean, and you don't need to take up your whole trunk with a big square box. In the Forenza's trunk, you could easily fit a 12 on each side of the trunk, leaving mostly open space. You can see detailed pics of my install at my CarDomain page [
federic0's 2006 Suzuki Reno on CarDomain - Page 2].
