Subaru WRX STi Harman Kardon -Adding a Subwoofer and Amplifier to Stock OEM Headunit

idoing Android Headunit (WIRELESS Carplay) | Harmon Kardon Subaru WRX Premium

Driving Pleasures | Sound System Upgrade | OEM Audio Plus Subaru WRX

WRX Speaker Upgrade Guide Part 1: Choosing a Speaker