Hello together, I ask here for my daughter. She bought her first new car, Kia Xceed 1.4l and let it lie down directly at the dealer, a rear diffuser and a flap-nauspuff. My question refers to the flap-nauspuff. Can someone tell me if I can check the function. Because according to my feeling it should become louder by pressing the button, only unfortunately the sound does not change at all. Has someone of you the flap-nauspuf f co-ordered? Tschau an alle René