{"product_id":"catback-b9-s4-sedan","title":"APR Audi S4\/S5 (B9) 18-25 Catback Exhaust System","description":"\u003cp\u003eIntroducing the APR Catback Exhaust System for the Audi B9 S4 and S5\u003c\/p\u003e\n\u003cp\u003eThe APR Catback Exhaust System for the Audi B9 S4 and S5 is a complete, high-performance exhaust solution that runs the entire length of the vehicle from the catalyst back. Inspired by the larger center-pipe design of the higher-output RS4 and RS5 models, this system is engineered to boost performance, elevate sound, and enhance aesthetics with customizable exhaust tips that are sure to make a statement. Crafted from premium materials and built with advanced manufacturing techniques, this system is designed to withstand harsh conditions and deliver lasting performance. Expect a bold, aggressive growl at wide-open throttle, along with an impressive gain of 10 horsepower and 12 FT-LBS of torque to all four wheels!\u003c\/p\u003e\n\u003cp\u003eUnmatched Design and Precision Engineering\u003c\/p\u003e\n\u003cp\u003eUnlike anything currently available, the APR system includes downpipes extending to the factory catalyst in the upper engine bay, making this a true full-system upgrade. We’ve minimized restrictions with smooth transitions, oversized piping, and straight-through mufflers and resonators. Constructed from mandrel-bent T304 stainless steel with a brushed finish and TIG welding throughout, this exhaust system is as durable as it is striking. Installation is hassle-free, thanks to precision-fit brackets, OEM-style slip clamps, and an included upgraded tunnel brace to accommodate the oversized piping.\u003c\/p\u003e\n\u003cp\u003eInspired by RS Performance\u003c\/p\u003e\n\u003cp\u003eLike the RS4 and RS5, this system features a reengineered exhaust routing design. It utilizes dual 2.5” (63.5mm) downpipes to dual 2.75” (70mm) midpipes pipes merging through a cast Y-junction into a massive 3.5” (91mm) midpipe, replacing the restrictive factory dual-pipe setup. The integrated Helmholtz resonator minimizes drone through a straight-through design with a sound-canceling port, ensuring no compromise in exhaust flow.\u003c\/p\u003e\n\u003cp\u003eThe system splits again via another cast Y into two rear, valve-controlled mufflers with sound absorption technology. These valves are fully integrated with the OEM control system, adjusting automatically to enhance sound during aggressive driving while maintaining a quieter profile during cruising. Finally, exhaust gases exit through dual cast Y-junctions into a quad 2.5” (63.5mm) system, terminating in 3.5” (91mm) lightweight, single-walled motorsport-style tips. The tips feature a polished stainless steel finish and a subtle APR logo for a refined touch.\u003c\/p\u003e\n\u003cp\u003eExperience the APR Difference\u003c\/p\u003e\n\u003cp\u003eDesigned for enthusiasts seeking the perfect balance of power, sound, style, and quality, the APR Catback Exhaust System for the Audi B9 S4 and S5 is a testament to engineering excellence. With its performance-driven design and durable construction, this system not only transforms your driving experience but also ensures years of reliable performance.\u003c\/p\u003e\n\u003ch3\u003eFeatures:\u003c\/h3\u003e\n\u003cul class=\"productpage_list\"\u003e\n\u003cli\u003eComplete catalyst-back system including downpipes, extending from the factory catalyst back.\u003c\/li\u003e\n\u003cli\u003ePerformance gains of 10 HP and 12 FT-LBS of torque delivered to all four wheels.\u003c\/li\u003e\n\u003cli\u003ePremium T304 stainless steel construction with TIG welding for strength and durability.\u003c\/li\u003e\n\u003cli\u003eOptimized flow through dual 2.5” downpipes, 2.75” midpipes, and a 3.5” midpipe.\u003c\/li\u003e\n\u003cli\u003eMandrel-bent brushed piping paired with electropolished cast splitters for a refined finish.\u003c\/li\u003e\n\u003cli\u003ePrecision brackets and slip clamps ensure accurate alignment and hassle-free installation.\u003c\/li\u003e\n\u003cli\u003eIncludes an upgraded tunnel brace to accommodate the larger piping.\u003c\/li\u003e\n\u003cli\u003eIntegrated Helmholtz resonator minimizes drone and enhances sound quality.\u003c\/li\u003e\n\u003cli\u003eValve-controlled rear mufflers dynamically adjust sound based on driving style.\u003c\/li\u003e\n\u003cli\u003eRemovable quad 3.5” motorsport-style polished tips with APR logo; optional styles available.\u003c\/li\u003e\n\u003cli\u003eSmooth transitions and straight-through components maximize performance by reducing restrictions.\u003c\/li\u003e\n\u003cli\u003eStrikes the perfect balance of power, sound, style, and quality for enthusiasts.\u003c\/li\u003e\n\u003cli\u003eFully emissions compliant for worry-free operation.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"APR","offers":[{"title":"Default Title","offer_id":53239700914475,"sku":"CBK0012","price":1332.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0064\/3645\/4465\/files\/Untitleddesign_9a8d9c3f-6312-49a7-a22b-eb1955b681e3.png?v=1778471573","url":"https:\/\/www.burton-racing.com\/products\/catback-b9-s4-sedan","provider":"Burton-Racing","version":"1.0","type":"link"}