Hi Bon,
I cough a lot throughout the day. And, especially when I nebulize 7% saline with my aerobika. I look at that as a good thing because the goal is to expel as much mucus as possible. I do not, however, cough up mucus when using my (HillRom) vest. And, interestingly enough, when I went for a second opinion on my BE and MAC, the pulmonologist who is an BE/MAC expert made a curious comment, saying that he did not think the vest does much. I am still using it 2x per day, just in case. But, it really doesn't seem to do much in terms of bringing up mucus even when I huff cough during or afterwards. I cough when there is mucus that has to come out. I could feel it in my lungs and it presents as a very pronounced tickle.