20,000? Try over 100,000
I would think it was really bad too.
But neither of us knows .001% of what he knows. Basically he said the sound is just cavitation.
The sound is not air going BACK into the turbo. The system doesnt feed the air back to it.
Think of it this way. You have a bottle. You screw a hose into it. You turn the water on. At some point you cap off the bottle so no more can get into it. The water doesnt back up, it just cant put any more in the system. The pump pushing the water in, will chug and makes noises, because it is trying to push more water in. But its not being forced to spin backwards or even stop.