these things get real nice and real loud. someone was doing 153's at the dash on music in his sebring with a no wall set up... SoundStream has the SPL-HX for daily streetbeating, with the lower fs etc, and in about a month there will be an SPL-HF (High Frequency) with a higher fs and more geared towards burping as opposed to the HX which is more of a bass racing type of sub.
I almost got these, but am going to try out the HF's instead... and I plan on running either two 1600d's per HF 12 or if I get 15's putting two 2500d's per.......