Woofers are obviously replacements, and no wonder -- the speakers are quite efficient, but the structure of the moving system isn't sturdy enough for the accelerations the drivers go through, and the voice coil former can get all folded. This happens when the foam rots and the owner doesn't notice and keeps playing them really loud (which is why he (and its almost a he) bought them to begin with). So then, when he contacts Infinity for replacements, they are $150 each. Well, since they were bought originally for their ability to make a racket, it hardly seems worth buying the exactly woofer that will maintain their specific frequency response (see above what their sine qua non was), so in go the car audio woofers.
On the bright side, they are loud and efficient...