Invidia (HS15STIGTP) N1 Stainless Steel Tip Dual Cat-Back Exhaust System for Subaru WRX/STI Fits 2015-Up Subaru WRX/STI 4 Door Pipe size: 76mm (3"), Tip size: 101mm (4") Constructed with high-quality SUS304 stainless steel, CNC-machined flanges, and manufactured with a polished finish Mandrel-bent stainless steel piping for maximum exhaust flow and reduced back pressure Twin outlet, single layer Stainless Steel tips