My ears although getting bad can tell me a lot. I’m on my third flowbench and I built it the way I wanted it. I can flow up to 36 inches of depression so I can really push things if I’m struggling with an issue. At 28 inches I can flow up to 460 cfm. I’ve bolted down heads just to take airspeed readings in a port. The Doctor J head (Airwolf) was one of the jumpiest heads I’ve ever had on my bench. My digital meter rolled 10-15 cfm at some lifts