Borla 22-24 Subaru WRX ATAK Cat Back ExhaustBorla 22 24 Subaru WRX ATAK Cat Back Exhaust This BORLA Cat Back system is designed specifically for the 2. 4L engine in the WRX. The 3" diameter single exit Cat Back system features Polyphonic Harmonizer technology which utilizes patented units that contain pipes of different diameters and lengths to create multiple exhaust notes that harmonize to deliver a clean, rich, full bodied sound and the aggressive ATAK sound with no drone in the cabin. The