pretty sure the magic formula with the L7 12's is 3.5 cubes, 35-38hz, and i'm not 100% certain on how much power they'll take, but i know polecat was feeding his 12's more than 1000w rms just for a daily driver, and i'm almost 100% certain that the 12's and the 15's use the same motor, which means you're not even scratching the surface