{"product_id":"apr-catback-exhaust-system-s4-s5-b9","title":"APR Catback Exhaust System - S4 \/ S5 (B9)","description":"\u003cp\u003e\u003cstrong\u003eAPR Part Number: CBK0012\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eFits Audi S4 18-25, S5 18-25\u003c\/p\u003e\u003ch2\u003eOverview\u003c\/h2\u003e\u003cdiv\u003eIntroducing the APR Catback Exhaust System for the Audi B9 S4 and S5\n\nThe 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!\n\nUnmatched Design and Precision Engineering\n\nUnlike 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.\n\nInspired by RS Performance\n\nLike 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.\n\nThe 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.\n\nExperience the APR Difference\n\nDesigned 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\/div\u003e\u003ch3\u003eFeatures:\u003c\/h3\u003e\u003cul\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\u003ch2\u003eSpecifications\u003c\/h2\u003e\u003ctable\u003e\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eBrackets\u003c\/th\u003e\n\u003ctd\u003ePrecise\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\t\u003ctd\u003e\n\t\tAPR\n\t\t\n\t\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eCategory\u003c\/th\u003e\n\u003ctd\u003eExhaust\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eClamping Type\u003c\/th\u003e\n\u003ctd\u003eSlip Clamp\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eClamps Included\u003c\/th\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eEmission Code\u003c\/th\u003e\n\u003ctd\u003e5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eExhaust Tip Color\u003c\/th\u003e\n\u003ctd\u003ePolished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eExhaust Tip Diameter\u003c\/th\u003e\n\u003ctd\u003e3.5 IN\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eExhaust Tip Finish\u003c\/th\u003e\n\u003ctd\u003eCarbon Fiber with Brushed Inlay\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eExhaust Tip Quantity\u003c\/th\u003e\n\u003ctd\u003e4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eExhaust Tip Removable\u003c\/th\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFinish\u003c\/th\u003e\n\u003ctd\u003eBrushed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eGrade Type\u003c\/th\u003e\n\u003ctd\u003ePerformance\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHangers Included\u003c\/th\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMain Piping Diameter\u003c\/th\u003e\n\u003ctd\u003e2.50 IN\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003c\/th\u003e\n\u003ctd\u003e2.75 IN\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003c\/th\u003e\n\u003ctd\u003e3.50 IN\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eT304 Stainless Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMuffler Finish\u003c\/th\u003e\n\u003ctd\u003eBrushed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMuffler Quantity\u003c\/th\u003e\n\u003ctd\u003e2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMuffler Type\u003c\/th\u003e\n\u003ctd\u003eHelmholtz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003c\/th\u003e\n\u003ctd\u003eSound Absorption\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePipe Bend Type\u003c\/th\u003e\n\u003ctd\u003eMandrel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePipe Material\u003c\/th\u003e\n\u003ctd\u003eT304 Stainless Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eProduct Type\u003c\/th\u003e\n\u003ctd\u003eExhausts (Catback Systems)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSub Category\u003c\/th\u003e\n\u003ctd\u003eExhaust and Tail Pipes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSystem Type\u003c\/th\u003e\n\u003ctd\u003eCatback\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTail Pipe Outlet Outside Diameter\u003c\/th\u003e\n\u003ctd\u003e2.5 IN\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTube Connection\u003c\/th\u003e\n\u003ctd\u003eButt Joint\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eValve Included\u003c\/th\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eValve Type\u003c\/th\u003e\n\u003ctd\u003eOEM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWelding\u003c\/th\u003e\n\u003ctd\u003eTIG\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eUPC\u003c\/th\u003e\n\u003ctd\u003e810009932550\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePart Number\u003c\/th\u003e\n\u003ctd\u003eCBK0012\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e\u003ch2\u003eEmissions\u003c\/h2\u003e\u003cdiv\u003e\u003cspan\u003e5\u003c\/span\u003e\u003c\/div\u003e\u003cbr\u003eThis part is legal for sale or use on Emissions Controlled Vehicles, Uncontrolled (Non-Emissions Controlled) Vehicles, and Racing Use Only Vehicles because it does not affect vehicle emissions and is not covered by emissions regulations.\u003ch2\u003eTech Resources\u003c\/h2\u003e\u003cdiv\u003e\n\u003cdiv\u003e\u003c\/div\u003e\t\u003ca href=\"https:\/\/documents.goapr.com\/b105b0ea51c8475b3f15db9e07492c681e476be9.pdf\" title=\"Instructions - tl100192_b9s4_catback_web.pdf\"\u003e\n\t\t\u003cdiv\u003eInstructions - tl100192_b9s4_catback_web.pdf\u003c\/div\u003e\n\t\u003c\/a\u003e\n\u003c\/div\u003e\u003ch2\u003eVehicle Applications\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e2018–2025 Audi S5 Sportback — 3.0L; United States\u003c\/li\u003e\n\u003cli\u003e2018–2020 Audi S5 (B9, F5) — 3.0L; United States\u003c\/li\u003e\n\u003cli\u003e2021–2024 Audi S5 (B9.5, F5) — 3.0L; United States\u003c\/li\u003e\n\u003cli\u003e2018–2019 Audi S4 (B9, 8W) — 3.0L; United States\u003c\/li\u003e\n\u003cli\u003e2020–2025 Audi S4 (B9.5, 8W) — 3.0L; United States\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment Requirements\u003c\/h3\u003e\u003cp\u003eInstructions - tl100192_b9s4_catback_web.pdf\u003c\/p\u003e","brand":"APR","offers":[{"title":"Default Title","offer_id":42081046364245,"sku":"CBK0012","price":1933.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0074\/3702\/5395\/files\/kies-motorsports-apr-apr-catback-exhaust-system-s4-s5-b9-1217554519.jpg?v=1768938088","url":"https:\/\/www.kiesmotorsports.com\/products\/apr-catback-exhaust-system-s4-s5-b9","provider":"Kies Motorsports","version":"1.0","type":"link"}