How much power does the APR Catback Exhaust for B9 S4 add?

APR measured gains of 10 horsepower and 12 lb-ft of torque at all four wheels with the Catback Exhaust for B9 S4 and S5. Those gains come from replacing the twin-pipe factory routing with an RS-style layout built around a 3.5 inch center pipe and straight-through mufflers and resonator.

Does the APR B9 S4 exhaust keep the factory valves?

Yes. The rear mufflers carry valves that stay fully integrated with the factory control system, so the car adjusts the sound automatically, staying quieter at cruise and opening up under aggressive driving. No extra controllers or wiring are needed to keep that behavior.

Why does the APR S4 exhaust include a tunnel brace?

The APR system uses a 3.5 inch center pipe in place of the twin factory pipes, which needs more room in the transmission tunnel. APR supplies an upgraded tunnel brace that clears the larger pipe while doing the job of the factory brace, so installation needs no modification.

Will the APR B9 S4 catback drone on the highway?

APR builds a straight-through Helmholtz resonator with a sound-cancelling port into the center pipe to minimize drone without restricting flow. Together with the valves closing at cruise, it keeps the car comfortable on long drives while the aggressive growl is saved for wide-open throttle.

Can the APR S4 and S5 exhaust tips be changed?

Yes. The quad 3.5 inch single-wall polished tips carry a subtle APR logo and are removable, and APR offers optional tip styles. Changing the look later means swapping tips rather than altering the system, so the rest of the exhaust stays in place.

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Description

APR Catback Exhaust for B9 Audi S4 and S5

APR’s Catback Exhaust for B9 Audi S4 and S5 borrows its layout from the RS4 and RS5, replacing the restrictive twin-pipe factory routing of the 3.0 TFSI with a single large center pipe. Front pipes start high in the engine bay at 2.5 inches, grow to 2.75 inch mid pipes and merge through a cast Y-junction into a 3.5 inch center section, before splitting again to valved rear mufflers and four 2.5 inch outlets. APR measured 10 horsepower and 12 lb-ft at all four wheels, with a bold, aggressive growl at full throttle. It suits the S4 or S5 owner who wants a genuine RS-style sound and look.

Design and Performance

A straight-through Helmholtz resonator with a sound-cancelling port tames drone without restricting the center pipe, and the rear mufflers combine sound absorption with valves that stay fully integrated with the factory control system, quiet at cruise and open when driven hard. Electropolished cast splitters keep every transition smooth, and an upgraded tunnel brace is supplied to clear the larger piping.

Features

Complete system starting from the upper engine bay
Mandrel-bent brushed T304 stainless steel with TIG welding throughout
Electropolished cast Y-junctions and splitters
Straight-through Helmholtz resonator with a sound-cancelling port
Valve-controlled rear sound absorption mufflers on the factory valve control
Precision brackets and OEM-style slip clamps

Specifications

Front pipes: Dual 2.5 inch (63.5 mm)
Mid pipes: Dual 2.75 inch (70 mm)
Center pipe: 3.5 inch (91 mm)
Outlets: Quad 2.5 inch (63.5 mm)
Exhaust tips: Quad 3.5 inch (91 mm) single-wall, polished, removable
Measured gain: +10 hp and +12 lb-ft at all four wheels

What’s Included

Front pipes
Mid pipes and cast Y-junction
Center pipe with Helmholtz resonator
Valved rear mufflers
Quad 3.5 inch polished tips with APR logo
Upgraded tunnel brace
Brackets and OEM-style slip clamps

Applications

Audi S4: B9 | 2018-2025 | 3.0L V6 TFSI
Audi S5: B9 | 2018-2024 | 3.0L V6 TFSI (Coupe and Cabriolet)
Audi S5 Sportback: B9 | 2018-2025 | 3.0L V6 TFSI

Notes

The Catback Exhaust for B9 S4 and S5 includes an upgraded tunnel brace that replaces the factory brace to clear the 3.5 inch center pipe
The factory valve control is retained
APR rates this exhaust as not affecting emissions, which makes it legal for sale and use on emissions-controlled vehicles

Frequently Asked Questions

How much power does the APR Catback Exhaust for B9 S4 add? APR measured gains of 10 horsepower and 12 lb-ft of torque at all four wheels with the Catback Exhaust for B9 S4 and S5. Those gains come from replacing the twin-pipe factory routing with an RS-style layout built around a 3.5 inch center pipe and straight-through mufflers and resonator.
Does the APR B9 S4 exhaust keep the factory valves? Yes. The rear mufflers carry valves that stay fully integrated with the factory control system, so the car adjusts the sound automatically, staying quieter at cruise and opening up under aggressive driving. No extra controllers or wiring are needed to keep that behavior.
Why does the APR S4 exhaust include a tunnel brace? The APR system uses a 3.5 inch center pipe in place of the twin factory pipes, which needs more room in the transmission tunnel. APR supplies an upgraded tunnel brace that clears the larger pipe while doing the job of the factory brace, so installation needs no modification.
Will the APR B9 S4 catback drone on the highway? APR builds a straight-through Helmholtz resonator with a sound-cancelling port into the center pipe to minimize drone without restricting flow. Together with the valves closing at cruise, it keeps the car comfortable on long drives while the aggressive growl is saved for wide-open throttle.
Can the APR S4 and S5 exhaust tips be changed? Yes. The quad 3.5 inch single-wall polished tips carry a subtle APR logo and are removable, and APR offers optional tip styles. Changing the look later means swapping tips rather than altering the system, so the rest of the exhaust stays in place.

About APR Tuning

APR was founded in 1997 and develops performance hardware, software and calibrations for Volkswagen, Audi, SEAT, Skoda and Porsche vehicles, from intakes, intercoolers and turbocharger systems to exhausts, brakes and suspension. It designs and manufactures from an 80,000 square foot headquarters in Opelika, Alabama, which it shares with Dinan as part of Holley Performance Brands, and delivers its software worldwide through a 24-hour automated system run from the same site.

Additional Information

The Bulletproof Automotive website contains many thousands of products purchased in multiple different currencies. All of the prices are entered manually and accurately at the time of entry. Due to the consistently fluctuating international exchange rates, at times prices may not be able to be honored at their original intended rate. We apologize for any inconvenience this may cause, unfortunately our website is unable to compensate dynamically for what can at times be volatile changes in the cost of items due to currency values fluctuating, changes in prices from suppliers, changes in shipping and import duties, and other factors. Rest assured that any order you place on line will be at zero risk to you in this area. If in the event your order cannot be fulfilled at the original intended website price we will offer you a 100% refund, no questions asked. We will continue to do our best to maintain updated prices and we will always continue to offer our price match guarantees as well to ensure our prices are always the best for you. In short, prices may change without notice. It is always advised to give us a call prior to placing your order online to confirm availability and to confirm current pricing.

Shipping Policy

Items that are in stock in the US, either at Bulletproof’s warehouse or at a supplier’s warehouse, are generally delivered within 7-10 days. Special order items from overseas take considerably longer. As a courtesy Bulletproof offers delivery estimates to our customers which take into consideration manufacturer availability and shipping schedule. These estimates represent our best guess based on previous orders from the manufacturer and do not in any way imply a guaranteed delivery window. Many manufacturers work in a “just in time” inventory system and often take 2-20+ weeks to produce an item once an order is submitted. All deliverable items are then sent to our Japanese warehouse. Bulletproof ships a minimum of one full ocean freight container every month from Japan, oftentimes more than one a month. Ocean freight takes an average of 4 weeks. Typically it breaks down to one week in Japan for paperwork and customs, two weeks by boat and one week in US customs/clearance. Due to the wide number of variables between manufacturer and shipping schedules, delivery estimates are simply just that – estimates. We attempt to estimate conservatively and we usually deliver faster than our estimates suggest. It is not Bulletproof’s policy to guarantee delivery time of any special order item, this is impossible for us to do. By ordering you acknowledge that there is no required delivery ETA and an order may not be canceled or altered due to manufacturing or shipping delays, all ETA’s are provided as a best guess only. Please review the full Terms & Conditions here.

BP Pricing Difference

We do pricing a little differently on our JDM brands and we believe in making things simple and clear. No hidden fees or surcharges. Every price you see includes the shipping cost to our office in Los Angeles, California and all the associated taxes/duties/fees for bringing the products into the US. The only shipping you ever pay is from our facility in the US to your location. Be wary of resellers that don’t include the cost of international shipping in their pricing on JDM parts. While we believe we’ll always have the lowest all-in price on JDM products, we offer a price match guarantee for all authentic parts purchased from authorized dealers as well. For many international customers, it’s much more affordable to ship from the USA than from Japan directly, as the air freight and ocean freight costs are typically much less. However, for customers looking to ship directly from Japan outside of North America, or domestically in Japan, we can provide pricing specifically for that scenario. Please do not hesitate to contact us with any pricing questions or concerns. Please email us at sales@bulletproofautomotive.com with any inquiries.

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APR Catback Exhaust for B9 Audi S4 and S5 [CBK0012]

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APR Catback Exhaust for B9 Audi S4 and S5

Design and Performance

Features

Specifications

What’s Included

Applications

Notes

Frequently Asked Questions

About APR Tuning

Reviews