The only two Hurricanes that I have experience with are the 640's with the 130hp Volvo and duoprop set-up, they top out at about 23 knots with no weight onboard. Add a few people and you're lucky to get 18 knots.
I also ran a refurb'd 733 with a 300hp Yamaha diesel and Yamaha outdrive set-up that topped out at about 31 knots unloaded and 24-25 knots with 6 passengers.
My reasons for converting these boats to 4-stroke outboards are increased deck space, less maintenance costs, less fuel consumption, less noise, smoother running, quicker plane times and higher top end speeds.
The same 640 that did 23 knots with the Volvo diesel ran 51 knots with a 2-stroke 250hp outboard and currently does 28 knots with a 115hp 4-stroke outboard.