a list of some of the best sq subs available, at all price ranges
IDMax
IDQ
DD (would require a very good box builder to get the best out of it)
Crystal CMPx2
BA (i think the inhuman is their SQ sub, quoted to do around 150db at very low hertz, something like 30hz)
Eclipse DVC/Ti (i wouldnt bother with Ti unless you have money to burn as the alums are almost as good, almost)
Infinity Perfects
Some would also include the w7, i personally wouldnt condiering you could probbaly get 2 of some of the subs mentioned here for the price pof 1 w7 if u looked harn enough.
my choice personally? difficult to say. they're all **** good. its like saying, would u like a viper, ferrari, or lamborghini? //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif