Amazon.com: Alpine SWR-8D4 8" Car Subwoofer : Electronics
Best Buy: Alpine Type-E 12" Single-Voice-Coil 4-Ohm Subwoofers (Each) SWE -12S4
Alpine SWE-1043 Type-E 10" 4-ohm subwoofer at Crutchfield
Alpine Type-E SXE1750S Car Audio 6.5-Inch Component 2-Way Speaker Set Of 2 Bundle + Alpine SXE-6925S 6x9 Inch 280 Watts 2-Way Coaxial Car Speaker Set Of Two - 1 Enrock 50 Feet
Alpine SWE-1242 Type-E 12" 4-ohm subwoofer at Crutchfield