KUFATEC Sound Booster Pro improves the sound of the existing active sound generator Powerful sound, no stopping at > 10 km/h or > 2300 rpm Module can be activated/deactivated via the supplied button Plug & Play installation Suitable for: Audi A4 8K (in combination with Audi original retrofit kit 8T0 071 901B) Audi A5 8T (in combination with Audi original retrofit kit 8T0 071 901B) Scope of delivery: Sound Booster Pro (module) Plug & Play wiring Notes: This product is not approved for use on public roads - use for racing purposes only. Only for cars with active sound generator The use of the APP / software and firmware update is not possible. For this, the software and hardware update with the article number 41174 is also necessary