Ultra Audio A Series 12" Single 4 Ohm 300 Watt Car Audio Subwoofer 600 Watt Max | eBay
DS18 SQBASS68 6X8" Under Seat Amplified Powered Car Subwoofer 600 Watts
Best Buy: JBL 12" 600-Watt Powered Subwoofer L8400P
Vandal 8 – 600 WATT 8 inch Subwoofer – Rogue Car Audio
BOSS Audio Systems BE8D Elite Series 8 Inch Car Audio Subwoofer - 600 Watts Max, Dual 4 Ohm Voice Coil, For Truck Boxes and Enclosures, Hook Up To Amplifier