my btls doesn't sound like shit, maybe if you don't have enough mids and highs to keep up with it then it won't sound good.
i don't like the higher frequencies on the btls, so my low pass is on 67hz.
lows are very good though, (i mean low lows like 30hz).
its not a mellow soft sounding sub but more of a hard hitting in your face sub
also if you are gonna run 2k+ watts on a single sub its gonna be hard to get some good SQ out of it