Best to read their webb site and Mark Kyles posts; from my experience like the company say set RPM for 5,500 at 2,500 ft straight and level and they are at their best, don't waste your time with any other setting. I tried 5,800 after being at 5,480 rpm thinking that would be good, I instantly learnt that it's a no, no; could not even get to 100 kts. Reset to 5,500 rpm and now 108 kts plus. I've fitted and adjusted 4 E-props now and many others and would not hesitate to recommend them over other brands around.