20 mph = 17.3 knots. I have a few tracks showing that speed on a F16. So yes an F16 will go that fast although it gets much harder with every additional knot.

I think the max recorded F16 speed is just over 18 knots right now. I think 20 knots is achievable by a skilled crew under pretty normal conditions, but that will be quite close to the real top speed of the design.

In special conditions like really flat water and such, a little more could be achieved but I dare not estimate how much more. By that time you are really sailing on the edge.

Wouter