Corsa Black Pro-Series Twin 3.5" Dual Rear Exit | 2011-2014 Subaru Impreza WRX / STI (14863BLK)2011 2014 Subaru WRX STI Corsa Black Pro Series Twin 3. 5" Dual Rear Exit CORSA Performance entered the exhaust category in 1998, re writing the rulebook for what a performance exhaust should be with the launch of our revolutionary RSC (Reflective Sound Cancellation) Technology. RSC Technology allows CORSA Performance the unique ability to selectively target and eliminate resonant frequencies that cause drone, by reflecting sound waves out of phase,