Firsth let me start by saying that I am huge into the car audio scene. I ran a high end car audio store for several years, so I am in no way new to the game.
The Exile XP12 subwoofer is an absolutely incredible subwoofer. It gets incredibly loud in even a small, sealed enclosure. The overall build quality is top notch. A very heavy, sturdy subwoofer with a beautiful look all around (including the cage and magnet, if that is your thing). The subwoofer comes with a sweet looking grill as well. It can be kept the "Exile Silver" color or can easily be painted to match your vehicles color.
Overall this subwoofer is a fantastic mixture of both sound quality and output. It has the ability to get very loud and still sound crystal clear. Give the subwoofer a nice 600w and enjoy!