PORSCHE CARRERA 4S 991 3.0I TURBO (420 HP) SOUND WITH SUPERSPRINT CAT-BACK SYSTEM WITH BYPASS VALVE Posted byStef + Friday October 21st, 2016 Available at PPE : Power Plus Engineering Supersprint Cat-back” system with bypass valve including: n. 248411 Connecting pipe kit with valve Right – Left (Weld on connection) n. 248304 Rear exhaust n. 248326 Endpipe kit Right OO 90 – Left OO 90