Let me point one thing out here, a sub is NOT meant to be heard from 2kms away, this is a cliche which we are forced to follow because of the " cool audio boys " who crank up the volume in public places and think they're going to score chicks this how, little do they know that those jerks are offending people instead.
The sub woofer im listenting to, and most of the subs ive listened to of the SQ club guys, could hardly be felt in the car standing next to yours if you're sitting in it.
So this mis-conception is all because of some stupid people who do not have any taste in music or equipment whatsoever, they just wana have the biggest sub, and the loudest boom in PUBLIC, what for is still to be answered.