Audiobahn AW1805Q 18" Dual 4 ohm Subwoofer - Sonic Electronix
For those of you who want more bass but don't want to sacrifice your spare tire or hatch space, I highly recommend this spare tire mount subwoofer : r/GolfGTI
New Audiobahn AW1571T 500W RMS 15 Inch Audio Subwoofer Retail $299.00 | Property Room
Audiobahn Car Subwoofers for sale | eBay
Audiobahn 10" Down-Firing Sub Unboxing and Testing | TQ10DF - YouTube
Autobahn 10-inch subwoofer box with amplifier built in for Sale in Rio Linda, CA - OfferUp