Subwoofer/Amp install on Mk5 Rabbit, GTI, Golf and Jetta - YouTube
VW Golf V 5 subwoofer Audio System M10EVO 300W RMS Hornhagen Car Audio
Amazon.com: NuIth Add an Amplifier Subwoofer Interface Adapter for VW 2004-2015, BMW 3/5, Audi 2002-2010 to Factory OEM Radio Stereo 2 Channel RCA Line Output Converter Kit : Electronics
Blade ICE - VW Golf MK5 speaker retrofit from Gladen Audio. This kit also works in Porsche 911's. ONE 200 Golf 5 Plug & Play 3-way System for VW 25 mm silk