Home >> Audi >> 2021 >> A4 Quattro Premium Plus, 2.0L Eng VIN B >> Repair and Diagnosis >> Accessories & Equipment >> Warning Systems >> Communication (1 Of 2) >> 91 Communication >> Sound System >> Subwoofer -R211-, REMOVING AND INSTALLING >> Subwoofer -R211-, REMOVING AND INSTALLING, AVANT G-TRON >> Tightening Specifications