Italian MC.72 seaplane made its maiden flight in July '31, too late to win the Schneider Trophy. In 1933 it set the world speed record: 424 mph. And in on 23 October 1934, with Francesco Agello at the controls it improved its own record, making 440 mph!
This achievement was beaten in summer '39 by two German planes - first He 100 (464 mph) and then Me 209 (470 mph).
Since 1989, the world speed record for piston-engined planes is far more impressive and far less famous: 528 mph (set by US F8F Rare Bear)