Tipsy are you referring to their page wording below?
Brumby engineers are currently working on the final design of the new AirCruiser and while only one AirCruiser has been produced to date, the highly successful military air training aircraft known as the CT-4 was derived from the AirCruiser design but up-graded to aerobatic standard. The CT-4 is used by the Royal Australian Air Force, the Royal New Zealand Air Force and the Royal Thai Air Force for ab initio flight training.
I'd be surprised if these figures were achieved, as in, often adding 100hp doesn't always add a stack of knots.
n its basic 210 hp piston configuration, the AirCruiser will have a cruising speed similar to or exceeding speeds of well-respected Cessna and Piper models such as the Piper Archer III and the Cessna 172s.
The 310 hp Continental will deliver cruising speeds and useful load capabilities similar to the highly successful Cirrus SR22 but at a significantly reduced capital cost.