Macchi Castoldi MC 72, David Miller, 1/72 Injection Kit

The Macchi Castoldi MC 72 is still the fastest piston powered seaplane. 

[This feat was achieved on 23 October 1934, when Agello piloted the M.C. 72 for an average speed of 709 km/h (440 mph) over three passes. This record remains (as of 2012) the fastest speed ever attained by a piston-engine seaplane.]