Mercedes C63 W205 Catted and Catless Downpipes & Mercedes A45S Decat Downpipe

When it comes to unlocking real performance from an AMG, few modifications deliver results as instantly as a downpipe upgrade. Whether you drive a twin-turbo V8 monster or a compact turbocharged hot hatch, improving exhaust flow transforms how the car feels, sounds, and responds. That’s why enthusiasts often look toward mercedes c63 w205 catted and catless downpipes as their first serious performance upgrade.

Let’s break down what these upgrades do, how they differ, and what you should know before installing one on your AMG.

Mercedes C63 W205: Why Downpipes Matter

The Mercedes-Benz C63 AMG (W205) features a handcrafted 4.0L twin-turbocharged V8 (M177 engine). From the factory, it’s already aggressive and powerful. However, stock downpipes include restrictive catalytic converters designed to meet global emissions standards. While necessary for compliance, they limit exhaust flow and turbo efficiency.

Upgrading to mercedes c63 w205 catted and catless downpipes reduces backpressure significantly. The result?

• Faster turbo spool
• Sharper throttle response
• Increased horsepower and torque
• A deeper, more aggressive exhaust note

Catted vs Catless: What’s the Difference?

Catted downpipes use high-flow sport catalytic converters. These allow better exhaust flow than stock while still reducing emissions. They’re typically preferred by drivers who want performance gains but need to remain road legal in certain regions.

Catless downpipes, on the other hand, remove catalytic converters entirely. This maximizes flow and delivers the most dramatic sound and performance increase. However, they may trigger a check engine light and are often not emissions compliant.

For tuned C63 W205 models (Stage 2 setups especially), upgraded downpipes are almost essential to achieve optimal power figures. Many owners report gains of 60–100+ horsepower with proper ECU tuning.

Mercedes A45S: Small Car, Big Potential

Don’t underestimate the Mercedes-AMG A45 S. Its 2.0L M139 turbocharged four-cylinder is one of the most powerful production four-cylinder engines in the world. From the factory, it produces impressive numbers — but like most turbocharged cars, it responds incredibly well to exhaust modifications.

Installing a mercedes a45s decat downpipe dramatically improves exhaust gas flow directly from the turbocharger. Because turbo engines rely heavily on efficient airflow, reducing restriction before the mid-pipe makes a noticeable difference.

Benefits typically include:

• Quicker turbo spool
• Increased mid-range torque
• Louder, sharper AMG crackles
• Stronger top-end performance

When paired with Stage 2 tuning, upgraded intake, and intercooler support, the A45S becomes an entirely different animal on both road and track.

Sound Transformation: What to Expect

One of the biggest reasons enthusiasts choose downpipe upgrades isn’t just power — it’s sound.

For the C63 W205, catless setups create a raw, thunderous V8 roar. Cold starts become more dramatic, and acceleration produces aggressive pops and bangs. High-flow catted versions provide a more refined but still muscular tone.

On the A45S, a decat system enhances turbo whistle and delivers sharper crackles in Sport+ mode. The exhaust note becomes deeper and more purposeful, especially at higher RPMs.

If you daily drive your AMG, it’s worth considering your tolerance for increased volume. Catless systems are significantly louder and may introduce slight exhaust smell during idle.

Tuning & Installation Considerations

Upgrading to mercedes c63 w205 catted and catless downpipes or a mercedes a45s decat downpipe almost always requires ECU tuning to maximize gains and avoid warning lights. Professional installation is strongly recommended because:

• Turbo connections require precision
• Heat shielding must be managed properly
• Oxygen sensor placement is critical

A proper Stage 2 remap ensures safe air-fuel ratios and optimized boost pressure.

Is It Worth It?

If you’re looking for one modification that delivers noticeable performance, sound, and driving excitement — downpipes are hard to beat.

For C63 W205 owners, upgraded downpipes unleash the full personality of the M177 V8. For A45S drivers, a decat setup transforms an already quick hatch into a track-ready rocket.

Ultimately, the decision between catted and catless depends on your goals: daily usability and compliance, or maximum raw performance.