On 3 June 1955, it was announced that the Fiat G.91 had been selected as the design with the most promise. Out of the submissions, the two winning projects were, in order: the Breguet Br.1001 Taon and the Fiat G.91. A third aircraft design was subsequently added: the Dassault Mystère XXVI. As a result of the G.91's selection, an immediate order was received for three prototypes and a total of 27 pre-production aircraft. Fiat quickly set about developing the concept to the prototype phase; noticeable changes in the design occurred during this phase, such as increases in the aircraft's maximum weight due to the addition of supplementary equipment and structural strengthening measures.