 After 1951 Unger sang regularly at the Bayreuth Festival.One of his signature roles was David from "Die Meistersinger von Nürnberg", which is documented on several recordings, including with Herbert von Karajan (1951), Rudolf Kempe (1951 and 1956), Hans Knappertsbusch (1952), Hans Rosbaud (1955), and Rafael Kubelík (1968), as well as a DVD of a 1970 performance conducted by Leopold Ludwig.Equally known was his Pedrillo in Mozart's "Die Entführung aus dem Serail", notably in the 1965 Salzburg Festival production staged by Giorgio Strehler and designed by Luciano Damiani, which was conducted by Zubin Mehta, and was kept in the festival's repertory for 10 years and was also shown at Milan's La Scala.