# APR 18-25 Audi S4/S5 (B9) Catback Exhaust System

The 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!

-   Smooth transitions and straight-through components maximize performance by reducing restrictions.
-   Removable quad 3.5” motorsport-style polished tips with APR logo; optional styles available.
-   Complete catalyst-back system including downpipes, extending from the factory catalyst back.
-   Mandrel-bent brushed piping paired with electropolished cast splitters for a refined finish.
-   Precision brackets and slip clamps ensure accurate alignment and hassle-free installation.
-   Premium T304 stainless steel construction with TIG welding for strength and durability.
-   Optimized flow through dual 2.5” downpipes, 2.75” midpipes, and a 3.5” midpipe.
-   Strikes the perfect balance of power, sound, style, and quality for enthusiasts.
-   Performance gains of 10 HP and 12 FT-LBS of torque delivered to all four wheels.
-   Valve-controlled rear mufflers dynamically adjust sound based on driving style.
-   Integrated Helmholtz resonator minimizes drone and enhances sound quality.
-   Includes an upgraded tunnel brace to accommodate the larger piping.
-   Fully emissions compliant for worry-free operation.

This Part Fits:

Year

Make

Model

Submodel

2019-2025

Audi

S4

Premium

2018-2025

Audi

S4

Premium Plus

2018-2025

Audi

S4

Prestige

2019-2024

Audi

S5

Premium

2018-2024

Audi

S5

Premium Plus

2018-2024

Audi

S5

Prestige

2020-2025

Audi

S5 Sportback

Premium

2018-2025

Audi

S5 Sportback

Premium Plus

2018-2025

Audi

S5 Sportback

Prestige

## Details

- **Price:** 2669.26 CAD
- **Vendor:** APR
- **Type:** Catback

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 2669.26 CAD | In stock |

## Images

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- Photo - lifestyle view
- Photo - out of package
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> Source: [Standard Auto Part](https://www.standardautopart.com/products/apr-18-25-audi-s4-s5-b9-catback-exhaust-system)
> Updated: 2026-07-04