Opel Astra OPC: A powerful car like the Astra OPC needs a powerful sound track that appeals to the emotional side of the high performance car enthusiast. That is why sound engineering played an important role in the development of the car. The engineers wanted to deliver the robust and masculine exterior sound typical of all Astra OPCs. They also wanted to recreate the jet noise like sound on the interior which OPC fans will remember from the last Astra when the driver accelerates from the mid to high rpm range. This is especially noticeable when changing up from third into fourth gear under acceleration.