I've read excellent reviews about the JL AUDIO CP208LG-W3V3, but can it beat in sound quality a 12 inches sub from other brands like Sundown ? Can it reach that low ?
JL products are of high quality and will perform as advertised.
That said it is a very small subwoofer system and there is a saying "space makes bass". If you have more space for subwoofer(s) you can get more output out of more cone area in a bigger box, if you are limited on space that JL should perform as well as anything in that space.