If its inside the pipe need make sure above elbow enough that when hangs down inside not acting as a dam and blocking air inside elbow or collector. Other than that wherever you want is fine
My question grew out of Frank's video, where he talked about the hose and the flow rate,
if you pinch it (the hose) with your finger.
That is, if the damper is at the end of the pipe (like a finger at the end of the hose), then it turns out that we accelerate the flow of the jet, but if we do the same in the middle, then the flow rate will not change so much.
Am i right, or not ?
Anytime you create a restriction in the passage, the pressure and flow rate is increased. Do it in the middle of the pipe and you are likely to create cavitation as well, but that is another issue.