Addressing the original question... I have a Infinity basslink in my saturn SC2, i chose it because of price and compactness, and it outperforms all others in that respect. For a 10" sub, box, and class D amplifier, the cost is very reasonable. It also takes up about 14" x 7" of trunk floor space when mounted vertically, which is many times less than a 10" in a 1 cu/ft box. If youre looking for good SQ and want to conserve space, the basslink is definately for you. If youre looking for any sort of SPL, sacrifice more space (and more money) for more sound. One note... the sub performs best when rear-oriented, and mounted VERY snugly to the trunk floor. (Its also very lightweight, making the mounting critical.) Just my 0.02.
Jeff