RE: 287mph on a Q500!!!!!
Well, there used to be a quickie advertised to have been radared at 208 mph, V-Vector or something like that. While is sounds like it was complete BS, but the story goes that they put a F1 engine on it and got the radar reading in a vertical dive to make the claim. The physics and math does make a pretty good case for the 208 figure to be factual.
An electric powered quickie might reach 200 in level flight if your setup has 3.4 kW at the motor.
To reach 287 (as if it would hold together), in level flight would take about 10 kW at the motor.