an L7 or an L5 would stomp that sub through the ground when it comes to loudness, but the kickers have little to no SQ, thus making them sound like garbage. that Diamond would sound very good, and get quite loud, but would not get nearly as loud as the garbage cans. lol
you could also take a look at some Arc Audio subs, i don't know the prices, but they are very nice as well.
Muddy isn't saying the Diamond isn't good. That sub rocks. I'd rather have a balance of loud and decent sound than just a loud muddy mess(No offense Muddy). For $300, look at the RE SX Ascendant Audio Avalanche, DDAudio, DBDrive, Eclipse Titanium, Alpine Type-X