Wrumer connects* to your car's internal computer and its speakers. It reads the cars RPM speed and throttle application and based on that plays an enhanced engine sound through your car's speakers. You can choose between multiple car engine sounds and effects, such as a Turbo Whistle and Backfires. *For the app to connect you also need the Wrumer device. You can get the Wrumer device at https://wrumersound.com.