"other than that, i would recommend getting mtx thunder 9500 subs. mtx beats everyone" You haven't heard that many subs if you think that. SPL wise they'd be hard-pressed to come anything close to Digital Designs 9500 or 9700 series, Eclipse Ti-Pros, Resonant Engineering X.X.X.s, JL Audio W7s, and numerous others.
Typo, I meant 9900 series, there wasn't a 9700. The Ti Pros aren't the loudest, but it's all in the setup. It would definately destroy an MTX 9500 in SPL. Not my choice for sound quality, though, overmotored and not for your typical box. Digital Designs is hard to beat in the SPL arena, and in a good box they can sound pretty good, too. W7s and Eclipse Tis (regular Tis, not Pros), as well as the Triple X are more for your SQL everyday sealed and ported enclosures (more like the MTX 9500). They will hit some high numbers if set up to do so, but all in all they're long linear throw subs designed to get loud and sound good over a wide bandwidth. SPL comps are more about getting the most out of a narrower frequency range, and piling power on at that frequency, linear x-max isn't as important as motor strength, material strength, power handling and matching the sub to the enclosure (or the enclosure to the sub).