Amazon.com: Alphasonik AS8DF 8 inch 600 Watts 4-Ohm Down Fire Shallow Mount Flat Enclosed Sub woofer for Tight Spaces in Cars and Trucks, Slim Thin Loaded Subwoofer Air Tight Sealed Bass Enclosure :
Amazon.com: KICKER Comp 10" (25cm) Subwoofer in Down Firing Encl, 4-Ohm, RoHS Compliant : Electronics
Amazon.com: Kicker 48TCWRT102 10" Slim Car Subwoofer Bundle with Rockville KRYPTON-M1 2000w Peak/500w RMS Mono 1 Ohm Car Amplifier Amp+Remote & Rockville RWK41 Installation Wire Kit with RCA's (3 Items) : Electronics