KYOSTAR Valved Sport Catback Exhaust System for 2014-2020 BMW F80 M3 F82 F83 M4 S55 3.0T Product Overview The KYOSTAR Valved Sport Catback Exhaust System is designed for BMW F80 M3 and F82/F83 M4 models equipped with the S55 3.0T Twin Turbo engine. This complete catback exhaust upgrade improves exhaust flow efficiency, reduces factory exhaust restriction, and enhances the aggressive performance character of the S55 platform while providing adjustable exhaust sound control