I can get stupid loud with 10's in the right box. It is all about the box. A set of good 12's in the right box will outperform average 15's in the wrong box and sometimes even in the right box. It is all about the careful match of subs to amp to box to install. Yuli asked what your goals are and I asked what the vehicle was, these are important things to know as this tells us what we should and should not recommend to you.

 

Yeah it's all in the box. It's just as important as buying the right sub.

 

2003 honda civic seats folded down when i pound ... I have 2 JL audio 12's in a 5.5cu box now ported to JL specs and they're pretty wicked, i'm louder than all my buddy's now but I have to step it up a notch just incase one of them upgrades hehehe
i'm after reasonable sound quality with a load of spl. budget is resonable too I'll just get the parts slowly over time... like the subs posted above one month and a motherload of an amp the month after that. it will take time i'm not going to blow load of money fast prolly go with the FI-BL's with cooling pack and a sundown 3000 or so... and open to suggestions on box ported or not and sealed ... right now i'm rear firing, it alway's seems to be better .. but huge box might fire up or forward?? thanks for the feed back everyone