http://www.dropbears.com/av/KFXart/articles/ca15.htm
"From this point only a very limited test program was run, the only significant flight taking place on May 25 1948 when Fl.Lt. J.Archer gently dived 4000 feet over Melbourne, levelling out at 5000 feet and at a speed of 502.2 mph.
_______ With a level flight speed of 448mph, the CA-15 was one of, if not the fastest piston engined fighter in the world. It certainly outperformed the P-51 Mustang (which at that stage was our primary fighter). It also outperformed the Spitfire XIV in a number of areas, most notably load and range.
_______ This was the last totally new piston engined fighter to undertake flight testing anywhere in the world. In that light, that it was arguably also the best fighter in the world is not surprising.
_______ However the jet age had arrived, and for piston engined fighters this was the end of the line. "
I was doing some research on the Supermarine Spiteful (Griffon engine, inward-retracting u/c, 494mph) and came across this interesting and fast Aust Mustang lookalike.