Hi guys, new to the forum.
Was just reading through the topics, and I can add something here: I've seen this before. Not on my Pathy but other car, it's related to a pressure relieve valve attached to the power steering pump. When the steering hits the limiter - right or left, the pressure in the system rises rapidly and this valve opens to allow excess oil to run back to the reservoire, or whatever it is called. Sometimes the valve makes those funny noises, have it checked and/or cleaned.
I hope that helps.