In this way Sazo would become the leading voice of the group as well as in charge of the lyrics. "El Congreso" would be the first album that the group would record. Sazo would be in charge of the lyrics that would be marked by the pacifist cut typical of the hippie subculture that marked the group in its beginnings. With Sazo as lyricist and singer, and Tilo González as composer and drummer, one of the most important creative pairs in the history of Chilean music would be formed. Due to the Pinochet's military coup, the next album would have to go through rigorous censorship filters, which Sazo would evade thanks to resorting to metaphors and rhetorical figures incomprehensible to the military. Finally "Terra Incógnita" would go out to the public in 1975 in the middle of the military dictatorship of Augusto Pinochet. Congreso would continue to develop its folk rock with increasingly complex lyrics and musical arrangements with the records "Congreso" and "Misa de Los Andes". In both Sazo would continue as lyricist and singer in addition to instrumental support with tarkas and recorders.