{"product_id":"apr-valved-cat-back-exhaust-system-audi-s4-b9-s5-f5-cbk0012","title":"APR Valved Cat Back Exhaust System","description":"\u003cp\u003eThe APR Catback Exhaust System for the Audi B9 S4 and S5 is a complete high-performance exhaust solution, running the full length of the vehicle from the catalyst back. Inspired by the larger centre-pipe design found on higher-output RS4 and RS5 models, this system is engineered to deliver increased performance, an aggressive exhaust note, and a striking visual upgrade.\u003c\/p\u003e\n\u003cp\u003eDesigned and manufactured using premium materials and advanced production techniques, the APR Catback Exhaust System is built to withstand harsh conditions while delivering long-term reliability. Under wide-open throttle, expect a bold, aggressive growl, along with gains of up to 10 horsepower and 12 ft-lb of torque delivered to all four wheels.\u003c\/p\u003e\n\u003cp\u003eUnlike conventional catback systems, the APR design extends all the way to the factory catalyst located in the upper engine bay, making this a true full-system upgrade. Exhaust restrictions are minimised through smooth transitions, oversized piping, and straight-through mufflers and resonators. The system is constructed from mandrel-bent T304 stainless steel with a brushed finish and TIG welding throughout, ensuring exceptional durability and a premium appearance.\u003c\/p\u003e\n\u003cp\u003eInspired by RS performance models, the exhaust routing has been completely reengineered. Dual 2.5-inch (63.5 mm) downpipes transition into dual 2.75-inch (70 mm) mid-pipes before merging through a cast Y-junction into a large 3.5-inch (91 mm) mid-pipe. This replaces the restrictive factory dual-pipe design and incorporates an integrated Helmholtz resonator to minimise drone without compromising exhaust flow.\u003c\/p\u003e\n\u003cp\u003eThe system then splits again via another cast Y-junction into two rear, valve-controlled mufflers featuring advanced sound absorption technology. These valves integrate seamlessly with the factory exhaust control system, opening under aggressive driving for enhanced sound and closing during cruising for refined comfort. Exhaust gases exit through quad 2.5-inch (63.5 mm) outlets, finished with lightweight, single-wall 3.5-inch (91 mm) motorsport-style tips featuring a polished stainless finish and subtle APR branding.\u003c\/p\u003e\n\u003cp\u003ePrecision-fit brackets, OEM-style slip clamps, and an included upgraded tunnel brace ensure a straightforward installation while accommodating the system’s oversized piping.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eTrue full-system catback design extending to the factory catalyst\u003c\/li\u003e\n\u003cli\u003eMandrel-bent T304 stainless steel construction with brushed finish\u003c\/li\u003e\n\u003cli\u003eIntegrated Helmholtz resonator for reduced drone\u003c\/li\u003e\n\u003cli\u003eValve-controlled rear mufflers with OEM integration\u003c\/li\u003e\n\u003cli\u003eQuad 3.5-inch (91 mm) polished stainless steel exhaust tips\u003c\/li\u003e\n\u003cli\u003eIncludes upgraded tunnel brace and OEM-style mounting hardware\u003c\/li\u003e\n\u003c\/ul\u003e\n","brand":"Go APR","offers":[{"title":"Default Title","offer_id":52519781040431,"sku":"CBK0012","price":3879.0,"currency_code":"AUD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0848\/3903\/9279\/files\/fcaafa84f8c2edda7395c460be3802d6cdb48e54.webp?v=1768179717","url":"https:\/\/www.prospeedracing.com.au\/products\/apr-valved-cat-back-exhaust-system-audi-s4-b9-s5-f5-cbk0012","provider":"Pro Speed Racing","version":"1.0","type":"link"}