The Audi S5 3.0T represents a sweet spot in the performance coupe and sportback market, blending daily usability with a rewarding driving experience. For owners looking to sharpen that experience, upgrading the exhaust system is one of the most effective and satisfying modifications. AWE Tuning, a Philadelphia-based manufacturer with a strong reputation in the European performance aftermarket, offers a cat-back exhaust system specifically engineered for the B8.5 and B9 S5 3.0T platforms. Priced around $1,500, this system claims to deliver a more aggressive, refined sound and a genuine increase of up to 15 horsepower at the wheels—all while maintaining a direct bolt-on installation. This guide provides a comprehensive look at the upgrade, covering performance expectations, sound characteristics, installation details, and overall value.

Why Upgrade to the AWE Tuning Cat-Back Exhaust?

The factory exhaust on the Audi S5 3.0T is designed with a global balance of noise regulations, cost, and comfort. It effectively silences the engine but leaves enthusiasts wanting more auditory and thermal feedback. The AWE Tuning cat-back exhaust system addresses these compromises with several key advantages.

Improved Sound Quality and Character

The most immediate benefit is the transformation of the exhaust note. The stock system produces a muted, somewhat sterile tone. The AWE system uses larger-diameter tubing (typically 2.5-inch or 3.0-inch depending on generation) and a free-flowing muffler design to release the 3.0T engine’s inherent character. The result is a deeper, richer sound at idle and part throttle, and a purposeful, aggressive growl under wide-open throttle. Importantly, AWE has engineered the system to minimize drone at highway cruising speeds, making it a more livable upgrade for daily driving. Many owners describe the sound as “European exotic” rather than uncouth or boy racer. The system is available in two configurations: Touring Edition (quieter, with a resonated mid-pipe for zero drone) and Track Edition (more aggressive, non-resonated, for a raw race-inspired tone). Both deliver a significant upgrade over stock.

Verified Performance Gains

AWE Tuning backs its 15 horsepower claim with third-party dyno testing. While cat-back exhausts typically offer modest gains compared to full turbo-back or downpipe upgrades, the S5 3.0T engine responds well to reduced exhaust backpressure. The larger, mandrel-bent tubing and high-flow mufflers allow the engine to breathe more freely, improving volumetric efficiency. On a properly tuned stock car, gains of 12–15 wheel horsepower and 10–15 lb-ft of torque are realistic. These gains are most noticeable in the mid-range to top end, sharpening throttle response and making the car feel eager to rev. Combined with a stage 1 ECU tune, the cat-back exhaust can unlock even more potential.

Superior Build Quality and Materials

AWE Tuning uses high-quality materials throughout the system. The piping is constructed from T304L stainless steel, which is corrosion-resistant and retains its appearance and structural integrity for years. The welds are consistent and smooth, and the system uses flanged connections with heavy-duty hardware. The mufflers and resonators are internally baffled to produce a specific sound without empty drone. The finish is either satin or polished stainless steel, and each system is backed by an industry-leading warranty (typically lifetime for the original purchaser). This level of craftsmanship justifies the $1,500 price point and ensures the exhaust will outlast the car.

Direct Fit and Simplified Maintenance

Unlike some aftermarket exhausts that require cutting or welding, the AWE system is a true cat-back design that bolts directly to the factory downpipes rear of the catalytic converter. It uses stock hanger locations and includes all necessary hardware. This makes installation straightforward for a capable DIY enthusiast and also retains full reversibility. The system does not require engine or drivetrain modifications, and it maintains the correct O2 sensor placement. Additionally, AWE provides a detailed installation manual and excellent customer support.

Tools and Materials Needed

Before beginning the installation, gather the following tools and supplies. Having everything on hand before lifting the car speeds up the process and reduces frustration.

  • Socket set: 10mm, 13mm, 15mm, 18mm sockets (3/8" or 1/2" drive)
  • Ratchet and extensions: Long and medium extensions, plus a swivel or universal joint for awkward angles
  • Torque wrench: Foot-pound range (at least 20-100 ft-lbs)
  • Jack and jack stands (or a lift)
  • Penetrating oil: WD-40 or PB Blaster for rusted bolts
  • Cutting tool (only if removing an aftermarket system with welded joints; for stock, unbolt only)
  • Flat-blade screwdriver: For prying off rubber hangers
  • Rubber mallet: To loosen stubborn hangers
  • Safety glasses and gloves
  • Exhaust system: AWE Tuning cat-back complete kit

Step-by-Step Installation Guide

The installation is a moderately difficult task, suitable for an experienced home mechanic. Expect to spend 2–4 hours working at a relaxed pace. The process is essentially the removal of the factory cat-back section and installation of the AWE system.

Step 1: Prepare the Vehicle

Park the S5 on a level surface, engage the parking brake, and chock the rear wheels. Lift the rear of the vehicle using a jack and place jack stands securely under the designated lift points. Ensure the exhaust is completely cool to avoid burns. Disconnect the negative battery terminal for safety, especially if you will be working near sensors.

Step 2: Remove the Stock Exhaust Section

Begin by removing the four bolts that attach the stock exhaust to the downpipes. These are typically 13mm or 15mm bolts. Spray them with penetrating oil fifteen minutes before attempting removal to combat corrosion. Next, spray the two rubber exhaust hangers located on each side (near the mufflers and center) and use a flat screwdriver or large pliers to pop the metal hanger rods out of the rubber isolators. Support the exhaust with a jack or a helper to prevent it from falling. Once all hangers are free, slide the stock system out from under the car. On some B9 models, you may need to loosen the heat shield near the rear diffuser for clearance. The stock exhaust weighs around 40–50 lbs, so handle it carefully.

Step 3: Prepare the AWE Exhaust Components

Unbox the AWE system and lay out the parts: front mid-pipes, rear muffler section, clamps, and hardware. Confirm you have the correct system for your vehicle (Touring vs. Track edition). Do not tighten any clamps fully yet—leave them loose to allow for adjustability. Apply a thin coat of anti-seize lubricant to the slip joints if provided (some AWE kits come with the pipes already assembled).

Step 4: Install the AWE System

Start by inserting the front mid-pipes into the downpipe flanges. Use the provided bolts (18mm socket) and tighten them lightly. Next, attach the rear muffler section to the hangers. The rubber isolators should slide onto the metal rods with a bit of force; a squirt of soapy water helps. Connect the mid-pipes to the rear section using the band clamps. Do not fully tighten the clamps yet. Adjust the exhaust tips so they sit evenly within the rear bumper cutouts. The tips should be centered and flush with the bumper contour. AWE includes adjustable hangers to fine-tune tip depth. Once alignment is satisfactory, tighten all clamps and bolts to the torque values specified in the manual (typically 35–45 ft-lbs for flange nuts and 40–50 ft-lbs for band clamps). Re-torque after a few heat cycles.

Step 5: Check for Leaks and Clearances

Lower the vehicle and reconnect the battery. Start the engine and listen for air leaks at the flange connections and slip joints. A small amount of exhaust vapor may escape initially until the seals seat; this is normal. If you hear a distinct hissing or ticking sound, re-tighten the affected clamp. Also, verify that the exhaust does not contact the underbody, heat shields, or suspension components. Rev the engine to 2000–3000 RPM to ensure there is no rattling or interference.

Potential Challenges During Installation

While the AWE system is designed for a direct fit, certain obstacles may arise.

  • Rusted hardware: Bolts on the downpipe flanges can seize, especially in regions with road salt. Use penetrating oil and allow time to work. If a bolt breaks, you may need to extract it or replace it.
  • Rubber hangers: Old rubber isolators can be stubborn. Spraying them with silicone lubricant or using a hanger removal tool simplifies the process.
  • Alignment: The exhaust tips must be perfectly aligned to avoid melting or damaging the rear bumper valence. Take your time during adjustment. If the tips are too low, the hanger brackets may need to be bent slightly for correction.
  • Heat shields: Some vehicles have heat shields near the rear suspension that require slight bending or removal for clearance. Mark them carefully before moving.

Post-Installation Considerations

After the installation, treat the exhaust to a proper break-in period. The sound and fit can evolve over the first few hundred miles.

Sound Break-In

The fiberglass packing inside the mufflers and resonators needs time to settle. When new, the system may sound slightly metallic or raspy. After 200–500 miles, the sound matures into its intended deep tone. Keep the volume moderate during this period if you want to avoid excessive harshness. The drone-free characteristics of the Touring edition usually only improve with break-in.

Periodic Inspection

Check all clamps and bolts after the first 100 miles, then again after 500 miles. Retorque as needed. Over time, inspect the system for soot buildup at connections (indicating a leak) or physical damage from road debris. The stainless steel finish can be cleaned with automotive polish and a microfiber cloth.

Warranty and Emissions Considerations

The AWE cat-back exhaust does not relocate or delete any catalytic converters, so it is legal for street use in most jurisdictions. However, check local laws. The system might affect your vehicle warranty only if a defect can be attributed to the exhaust, which is rare. That said, always keep the stock exhaust in case you need to return the vehicle to standard for dealer visits or inspections.

Cost vs. Value: Is It Worth $1,500?

At approximately $1,500, the AWE Tuning cat-back exhaust is a premium product in a competitive market. Competing systems from Milltek, Borla, and Akrapovič range from $1,200 to $3,000. The AWE system offers a proven balance of sound quality, performance, and build quality. For many owners, the combination of a 10–15 horsepower gain, a transformative sound, and the prestige of an AWE system justifies the expense. Additionally, the resale value of a well-documented aftermarket exhaust can be reasonably high, and the system itself can be sold separately if you ever sell the car. For those seeking even more sound, pairing the cat-back with a downpipe or test pipe is a common next step—but the cat-back alone provides a significant upgrade.

For readers considering this upgrade, the following resources provide more detailed information.

Conclusion

The AWE Tuning Cat-back Exhaust system is a high-quality, well-engineered upgrade for the Audi S5 3.0T. It delivers a noticeably more aggressive and refined sound, a genuine performance increase of up to 15 wheel horsepower, and a robust build that will last the life of the car. The installation is manageable for a confident DIY mechanic, and the result transforms the driving experience without sacrificing everyday usability or street legality. For a $1,500 investment, the AWE cat-back exhaust represents one of the most rewarding modifications available for the S5, providing an auditory and performance upgrade that truly enhances the car’s character. Whether you choose the refined Touring or the raw Track edition, this exhaust is a worthy addition to any enthusiast’s garage.