I'm planning on upgrading my system within the next month or so, currently I have a Kicker L5 15" running on 1k watts rms in a 4 ft^3 tuned around 40 hz. It's gets low, but doesn't get low enough... I'm leaning towards the Sundown X-18, or maybe a Sundown SA-15. I've heard the X series can take a hell of a lot more power than what they are rated for (1250W) I believe. Which is what i'm leary about, would I be better off getting a X-18 wired down to 1 ohm at 1400RMS, or go with a SA-15 wired at 2ohm at 1k rms? How much can these subs truly take?