Maybe the liquid force thruster! Someone on this forum apparently reached 50km/h with his gear set up with the thruster. Plus, the specs say it is a fast foil.
I have it and yes, I do think this speed is possible. I must say that I did not measure it with gps but my first foil did 37km/h and this one feels a lot faster.
Do you know if there is any way to fit the thruster wings on a regular LF fuselage or do you need the profiled fuselage that comes with the thruster kit?