Yeah, a 12K has more potential to get louder than a Type-R 15 //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif
Mark ported a pair of SWR-1541Ds for that one guy out in Alberta (I believe it was like 3 ft^3/sub tuned to 27 Hz) with 1600 or 1800 RMS and apparently he was hitting high-140s/low-150s and it suppposedly sounded pretty good, too ...
Give it more power, 2-4 ft^3 net volume, and tune it low (25-30 Hz) //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif