Defending champion GSA became the first team in tournament history to win back-to-back titles in the fifth annual $50,000 National 12-Goal Tournament Saturday at Grand Champions Polo Club. After a close first half, GSA (Henry Porter, 2, Santino Magrini, 3, Toro Ruiz, 5, Nachi Viana 2) dominated Beverly Equestrian (Bill Ballhaus, 0, Hilario Figueras, 2,