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
19+) - 2020 - HK System Subwoofer upgrade to Spare Tire Sub? | Subaru Forester Owners Forum
Amazon.com: Gravity Warzone WZ10US 10" Pro Audio Active Compact Spare Tire Slim Aluminum 1000 Watts 2 Ohm Subwoofer Powerful Loud Speaker with Bass Volume Control Knob : Electronics