I don't know I took the stem off the pipe and it whistles when I puff on it.What part of the stem?
All of my undies are seersucker.For texture I prefer seersucker.
This is the answer. Unless of course it is at the bit which still means that you could sand the airway a bit and it should make it better.There's a burr or edge that is acting as a reed, as in a woodwind instrument. First try a bristle pipe cleaner, to clear away any loose bit of tobacco or stem material. If it still whistles, gently sand edges in the stem airway; you don't have to take off much at all, just sand off that little vibrating edge. Some pipes will just whistle, but I think you can soften the sound so it is barely noticeable.