He is claiming that a 2.7m SIB(airdeck) with a 10 HP 2/str engine does 43 mph, and would go faster in flat water
I can't imagine it going significantly faster than my 3.9m boat (solid hull) with 20HP. Which tops out at 22 knots (25 mph / 40 kph). It might get a knot of two with a better prop etc... ...so I would suggest he probably managed 43 km/hr not miles per hour.
Oh and if he could do 43 mph in a SIB he wouldn't be getting a PWC for more excitement!