Muniz was a two-year captain of the Crusader men's hockey team during the 1984-1985 and 1985-1986 seasons. He set a school single-season record with 53 assists in 1984-1985 and his 86 points that season were second all-time at Holy Cross. He was named All-New England and second team Titan All-America that year. Muniz also totaled 54 points on 26 goals and 28 assists as a senior.
Over the course of his collegiate career, Muniz totaled 207 points on 87 goals and 120 assists, while recording five career hat tricks. He finished his career ranked second all-time at Holy Cross in assists, tied for third in points and sixth in goals. Following the completion of his career as a Crusader, Muniz was drafted by the Virginia Lancers of the Atlantic Coast Hockey League and All-American Hockey League, with whom he totaled 80 goals and 76 assists in two seasons.