I think that 20% is too low. I worked into mine by looking in normal mode. I set my 25% collective stick setting for 0 deg pitch, with hover at 5 deg at mid stick. I did power descents as in setting up for autos at 1/4 stick and listened for head speed. I added about 5% and this is what I set for the bottom of my V-Curve. It ends up between 35 and 48% on my 3 helis. You just don't want to overspeed or drop the head speed too much.