So, new compressor installed and.......still makes the same sound. So it would appear that the one Cummins shop I spoke with was right. They seem to make some clatter on this set up for some reason. Could be the sound of the pulses magnified through the steel air line to the dryer but in any case there doesn't seem to be reason for panic if any of you should notice the same sound I heard. Cummins was gracious enough to cover it under warranty as a precaution, so many thanks to them. In fact I have to say that the service I have recieved from Cummins has been excellent. Any phone conversation or information exchange back and forth has been second to none. And also for Forest River has been excellent with anything from questions to technical help regarding the coach itself. In having only onwned this coach for 4 months now, I feel secure knowing that these two companies that make up our coaches (and Freightliner, but they are a no brianer for a great chassis), not only make a great product but back it up as well.