A Turin entrepreneur, Giusti was in 1935 together with Giorgio Ambrosini one of the animators of the Scuderia Subalpina founded by Count Luigi della Chiesa. The team then served as Maserati's official team. Following the meeting with Roselli, then under the Scuderia Ferrari, Giusti proposed the mass production and marketing of the Testadoro for the Fiat 500 through his own company, the Casa dell'Auto di Torino. After three intense years of racing and victories, including racing himself as a driver of his cars, Giusti retired from racing in 1949 following the death of his partner Roselli, which took place in the autumn of that same year. On his last years, he became an internationally renowned artist as a painter.
Engineer, formerly in force at Scuderia Ferrari, he was in 1935 among the designers (together with Luigi Bezzi and Enrico Bertacchini) of the infamous twin-engine Alfa Romeo 16C, commissioned by Enzo Ferrari to counter the dominance of German cars in the Grand Prix of the time. Roselli designed a cylinder head with hemispherical combustion chambers and radial valves for the transformation of normal engines of the Fiat 508 "Balilla" into racing engines for the Sport 1100 class. Following the entry into the company with Giorgio Giusti, he designed the cylinder head with 750cc displacement for the transformation of the quiet Fiat 500 engines. He died in the autumn of 1949 in a car accident together with Dante Spreafico, a driver with several Mille Miglia behind him.