The South Texas Popular Culture Center (TexPop) will turn up the volume on its current “Metal Mayhem” exhibit with a concert uniting the musicians who helped make San Antonio the 1980s’ “Heavy Metal Capitol of the World.” The Sunday, April 8, show will assemble performers from South Texas’ S.A. Slayer, Watchtower, Juggernaut and Militia, among others, to shred through the songs that made them headbanging legends. Those still suffering tinnitus from that 1980 UFO-Triumph show at Convention Center Arena will likely recognize the performers in the supergroup dubbed the South Texas Legion: Chip Alexander, drummer for Karion and Militia; Bob Catlin, guitarist for S.A. Slayer and Juggernaut; Bobby Jarzombek, drummer for Fate’s Warning and Juggernaut; Jason McMaster, vocalist for Watchtower and Dangerous Toys; James Rivera, vocalist for Helstar; Mike Soliz, vocalist for Militia; Art Villarreal, guitarist for S.A. Slayer and Karion; Scott Womack, bassist for Juggernaut. The TexPop exhibit, which runs through April 22, showcases photos, art, video and memorabilia documenting San Antonio’s thriving ‘70s and ‘80s heavy metal music scene, including displays on DJ Joe “The Godfather” Anthony, promoter Stone City Attractions and myriad local bands.