When it comes to subs, quality over quanity will make a HUGE difference. I had 2 kicker l7 that were knocking but I met up with this guy who really knew what he was doing. I sold one and kept the other. He built me a box for $200 made out of some special type of wood. It was amazing, I had 1 12'' kicker that was louder than the 2 I had before. So my advice is to invest in a box and not the flea market junk like in those pictures and just get 1 12' or 15' and you will be straight.