cause it doesnt sound that good for SQ, or SQL for that matter. the W6v2 sounds ten times better than the W7 but thats just my opinion. the W7 doesnt sound too great sealed to me, and ported it has nowhere near the SQ of a W6v2 sealed.
w3's sound ok but don't have the spl i die for... i'm sure 2 15's would have no problem satisfying spl needs though... but sealed they really are pretty weak.