Don't think I've ever used one on a normally aspirated Engine. They do give an indication of engine condition but so does revs on take off for any fixed pitch prop., USE Coarse and Fine with Pitch to avoid confusion. I got little if anything from that presentation, in stryle or substance. Altitude and air temp are the biggest factors in engine and aircraft performance for unboosted engines. You should have a fair idea what the Power at various Levels is on full throttle.. Nev