If you are looking for a nice "light" way to add some depth to your system take a look at something like this; a powered Sub (this one is made by Clarion). Lots of positive features, small, easy to install, no guesswork in trying to matchup an amp & sub. They generally have a really nice clean sound. So unless you are out to blow the windows out on your block this might be a good solution.
The Powerwedge sounds really good. A number of models to choose from including single drivers that are ported. Perfect for lower power amplifiers and ultimately lighter weight that won't bog down your car.
I like my A1 poweredge from 1999, it is heavy in the trunk and it's a good ballast, i bolted tied it down to the bolt downs on the trunk, and it makes sure it doesnt move..
Without it, my backend slides around too much, with this in the trunk, it slides, but i have better control.