I just had my Smart Madness subwoofer box installed. I wanted a clean system. I didn't want huge speakers that take up all my storage space. So I threw in an 8" Kicker and a really clean amp. I used an MB Quartz Discus amp. THD is <.06% I am running a good 200 watts on the subwoofer alone. Oh, still running the stock radio.(I know, that's another thread)
The results sounds very good. The subwoofer has a lot of punch for its size. Most the time you can't tell where it's coming from. I think it is definitely worth the money for those who want good sound without losing any storage space. The key here I think is having a really good clean amp.
Cisco