The Invidia WRX Exhaust System is constructed with fully polished SUS 304 stainless steel. The flex joints are used to dampen the cat-back exhaust system from engine vibration. The exhaust features CNC machined flanges, robot TIG welded, and computerized mandrel-bent tubing for the straightest possible line and the lease amount of bends. Tip Size: 101mm Pipe Size: 76mm Will not work on WRX Sedan. Only for the Hatchback.