Can anyone Rate this subwoofer?

Hey, I want to purchase a 12" subwoofer for my car. I was thinking the JL Audio W3. A few specs include.........500 RMS....single 4 ohm......n ha thts about it............What do you think? But, I dont know whether to get the JL W3 or the Boston Acoustics G5? Please note, I'm looking for a clean sounding sub. Not one that I am going to turn up all the way so my mirrors shake while I am driving down the road. And also, there is no recommended enclose type? I know a sealed will help me so I can get a tight, clean sound. But, I have heard its hard on your sub? Any suggestions? thanks.