Amazon.com: Pyle 6.5 Inch Mid Bass Woofer Sound Speaker System - Pro Loud Range Audio 300 Watt Peak Power w/ 4 Ohm Impedance and 60-20KHz Frequency Response for Car Component Stereo PLG64 : Electronics
Pyle Plw10bl 10 Inch 600 Watt 4 Ohm Impedance Car Audio Stereo Sound System Power Subwoofer Speaker With 1.5 Inch High Temp Kapton Voice Coil, Blue : Target
What Impedance Should I Wire My Subwoofer? - Sonic Electronix Learning Center and Blog
DS18 EXL-X15.4D Subwoofer in Black - 15" Speaker, 2,500 Max Power, 1,250 RMS Power, Fiber Glass Dust Cap, Red Aluminum Frame, Dual Voice Coil 4+4 Ohm Impedance, Treated Rubber Edge (1 Speaker) : Everything Else
impedance rise? - Subwoofers / Enclosures - #1 Car Audio Enthusiast Forum in the world! | SMD | Meade916
How to Wire a Dual 4 ohm Subwoofer to a 2 ohm Final Impedance | Car Audio 101 - YouTube
The Subwoofer DIY Page - Projects : Using Impedance Graphs
JBL STADIUM122SSI 12" High Performance Automotive Audio Subwoofer with Selectable Impedance - Creative Audio