I call bullshit on every person saying the solo x *****. I challenge you to find a YouTube video of something that is the same amount of subs shaking a car like what I've seen. Cuz you can't. 5000 watts rms. Have fun finding better
Where do I even start...
A car rattling is the worst possible way to gauge how loud a system is. Have you ever been to an actual car audio competition before? Have you ever noticed how the guys who utilize sound deadening in their cars end up with a system that rattles WAY less than yours and meters WAY higher than yours? Then again, if you had gone to a car audio competition before (a legitimate one, not the one at your high school), you probably wouldn't still be saying that a square sub has magical pixies that protrude from the corners that circle subs don't have, and thus make the bass travel further.
Let me make things simple for you. A cone of a subwoofer pushes air, and the pressure that is created is what we meter at a competition. Now, a circular cone that is 12" in diameter versus a square sub that is 12" in diameter will have less cone area. Do the math for yourself: area of a square = d^2 (or diameter squared, if you don't understand geometry); area of a circle = πr^2 (pi times radius squared). Insert 12" for the diameter and 6" for the radius (half diameter). You'll see that the square sub has more cone area. The greater the cone area, the greater the output, all other things kept constant. This is why you think square subs are the holy grail, because of the way they are measured.
Now, you must be thinking, "I'm right, Kickers are better!" Except, you fall short. Sure, a given sub with a square cone versus the same sub with a circular cone will have more output, but that's as far as things go. You can buy a 15" circular sub from, lets say, DC audio, for much less. This sub from DC will be more reliable, have better sound quality, and be able to handle more power (obviously, dependent on the model). So now, you can buy a sub that costs more and doesn't perform better, or just quit acting like square subs have some magical properties that make it louder. Use your head, and you'll see how unbelievably ignorant you sound by thinking that.