2 JL 13.5 W7 Subs using a 500/1 per coil (4 500/1's) make sure you use a headunit that puts out over 4 volts thru the preouts (kenwood, eclipse, alpine + PXAH701) Shitload of money, but that's the loudest and deepest bass I've ever heard. The setup we had was running off of Kenwood Excelon DDX8017 pushing 5 volts preout.