What type of SPL's do you guys commonly see (or have the capability to reproduce) with your DIY subs? I originally bought 2 tempests, with the intention of building two sonosubs. I completed the first, and I can't imagine needing a second! If my friends ask for some demo's, I usually crank up a 15 Hz sine wave, which gives the couch/room/window a very nice rumbling. I then run some very slow waves from 15-500 Hz. Don't have an SPL meter so I can't get any readings though It unfortunatly doesn't sound to swell, because at those level's, everything is rumbling/shaking/rattling. At every frequency something else starts making noise Compared to the velodyne CHT-15 which I had before (which according to some ht forums is supposed to be a very nice sub) mr. tempest is much much better. Not to mention, much much cheaper!