JL Audio 13TW5v2-4 Shallow-mount 13.5" 4-ohm subwoofer at Crutchfield
8" Powered Subwoofer Slim Compact Design 200W Dynamic Bass for Home Theaters 819603019506 | eBay
Amazon.com: Pyle 8-Inch Low-Profile Amplified Subwoofer System - 600 Watt Compact Enclosed Active Underseat Car Audio Subwoofer with Built in Amp, Powered Car Subwoofer w/Low & High Level Inputs PLBX8A,Black : Electronics
Two Infinity REF1000S Reference 10 Inch Low profile Subwoofer with SSI (Selectable Smart Impedance) - Creative Audio
Pyle 8-Inch Low-Profile Amplified Subwoofer System - 600 Watt Compact Enclosed Active Marine Underseat Car Subwoofer with Built in Amp, Powered Car Subwoofer w/Low & High Level Inputs PLMRSBA8,Silver - Newegg.com
10-Inch Low-Profile Amplified Subwoofer System - 900 Watt Compact Enclosed Active Underseat Car Audio Subwoofer with Built In Amp, Powered Car Subwoofer w/ Low & High Level Inputs - Pyle PLBX10A - Walmart.com