Stone Sour Tap ex-Dream Theater Drummer Mike Portnoy for Rio Gig!Stone Sour Tap ex-Dream Theater Drummer Mike Portnoy for Rio Gig!Stone Sour have enlisted the drumming prowess of ex-Dream Theater stickman Mike Portnoy for their upcoming one-off show at the Rock in Rio Festival in Brazil on Sept. 24.Mardi GrasMardi Gras