nothinbutcowboy
+1y
For best Boom for you buck look at the Kicker L7's... they are loud as snot... as for sound quality... meh. They need lots of power though.
I personally am an MTX man for subs... Mtx used to be a shitty company, but they are pretty big time now, they're shit is real solid... I'm planning on running 2 9500 15's in a blowthrough.
For competition: a single 15... like an old school juggernaut in a bigass box will hammer! I work at A&B sound. I'm an installer. My manager had a 16 cu ft. box in a 93 cavalier with one juggernaut 15 and about 4 thousand watts... he competed with that.
For loud lows (nicer sounding bass) you need to tune a ported box really low (like 28-35 Hz) ... for SPL you wanna tune it around 60 Hz.. (which also sounds like shit... [actually its loud for some techno shit.]) Don't build a bandpass box, they are loud but they sound like shit, and they eat woofers.
Sealed is more "accurate" sounding... but wont give you the boom i think you are looking for.
10's for punchy bass... 15's for hip hop stuff.
Instead of having lots of woofers, and starve them for air space, have fewer woofers and give them lots of air.
Just my advice