I have the same problem in my 2005 with the top down, I don't think there is any way of altering the volume, but i could be wrong. If you find that there is a way of altering the volume be sure to post how you did it.Is there any way to turn up the volume on the parking assist sensors for the 2007 9-3? With the top down, I can barely hear them. Any way to make them louder? Thx.