Yes they do. Two guys at my airfield take theirs out togethe and they sound really cool out there. The faster or bigger the plane the louder they howl. I am guessing the howling is from the wind traveling over the wings. The first time I heard it, I was pretty new to flying and it scared me because I thought something was wrong with my plane. I am actually going to buy one now because I think that sound is awesome coming off those 90 size planes.