The engine was designed by Piero Prampolini who later went on to design the Benelli 500GP of 1972. The 1956 175cc Catria seen here is in MSDS (Moto Sportive Derivate dalla Serie) tune. MSDS was a Formula 3 category for Junior-class riders and a fiercely contested series. It was common for owners of the time to add the colourful "victory" decals to their (older) bikes over the years. Guy Webster collection, USA.
Courtesy Phil Aynsley Photography