Reduce Noise from SBC Pump on 2004 Mercedes-Benz E500

The SBC Brake pump is very loud on this car and operates frequently (can be heard over the engine noise). I've been told by a dealer service rep a vent line (installed on later models) will reduce the noise level to half. What are your thoughts?

Asked by for the 2004 Mercedes-Benz E500
Check the forums for such modifications. They maybe on to something.