WARNING: This product can expose you to chemicals that are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information, visit www.P65warnings.ca.gov.The APR Rear Catback Exhaust System (CBK0057) is a premium exhaust solution for the Audi B9 SQ5, designed to deliver a deeper, more aggressive growl while significantly improving exhaust flow. Inspired by the high-output routing of the RS4 and RS5 models, this system replaces the restrictive factory dual-pipe setup with an oversized single 3.5" (91mm) mid-section. Whether used as a standalone "midback" upgrade or paired with the APR Midpipe System for a full 10 AWHP gain, this system offers the ultimate balance of performance and refined acoustics.
Constructed from mandrel-bent T304 stainless steel, the system features a valve-controlled rear muffler that integrates perfectly with the factory OEM control system. When the valves are closed, exhaust gases pass through a straight-through muffler for a civilized cruising experience; when open, the gases bypass the muffler for maximum volume and performance. The kit even includes a specialized upgraded tunnel brace to accommodate the massive 3.5" piping, ensuring a perfect, rattle-free fitment.
Key Features:
- RS-Inspired Engineering: Utilizes a cast Y-junction to merge dual 2.75" pipes into a massive 3.5" center section for superior flow.
- Dynamic Sound Control: Fully compatible with factory exhaust valve actuators to switch between a refined cruise and an aggressive growl.
- Verified Power Gains: Delivers +5 AWHP and +6 AWFT-LBS standalone, or +10 AWHP and +12 AWFT-LBS when paired with APR Midpipes.
- Straight-Through Design: Minimizes backpressure with smooth transitions and a high-flow rear muffler featuring Helmholtz resonators to eliminate drone.
- Premium Construction: TIG-welded T304 stainless steel with a brushed finish and electropolished cast splitters.
- Stealth downturns: Features dual 3" downturn exits that maintain a clean look behind the factory bumper.
- Complete Hardware Kit: Includes an upgraded tunnel brace, precision brackets, and OEM-style slip clamps for a professional installation.
- Emissions Legal: 100% emissions compliant as it installs after the primary catalytic converters.
Technical Specifications:
| Feature | Specification |
|---|---|
| Main Piping Diameter | 3.5" (91mm) Primary Section |
| Inlet Diameter | Dual 2.75" (70mm) |
| Material | Brushed T304 Stainless Steel |
| Exhaust Valves | OEM Integrated / Electronic |
| Exit Style | Dual 3" Hidden Downturns |
Compatibility Note: This system is not compatible with vehicles equipped with the factory Air Suspension or S Sport Package due to clearance issues with the oversized 3.5" center section.
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