Mercedes W177/C118, A45/A45S/CLA45/CLA45S AMG Catted Downpipe With Heat Shield

Free up the M139 in your Mercedes-AMG A45 S or CLA45 S without giving up emissions control entirely. This catted performance downpipe replaces the restrictive factory unit with a high-flow sports catalytic converter, woven heat shielding over the downpipe section and a polished connecting pipe with a braided flex joint.

The M139 is the most powerful series-production four-cylinder ever built, and the factory downpipe is the first thing holding it back. This version delivers most of the gain a catless pipe offers while keeping a working catalyst in the system, which is what makes it the sensible choice on a car that still has to do the daily drive.

Manufactured from premium T304 stainless steel and precision TIG welded throughout. The sports catalyst keeps the exhaust note cleaner and considerably less raspy than a catless pipe, and dramatically reduces the chance of a check engine light or a failed visual inspection.

Key Features

High-Flow Sports Catalytic Converter
A far less restrictive catalyst than the factory unit, retaining emissions control while releasing most of the flow a catless pipe offers.

Woven Heat Shielding
Wrapped over the downpipe section, keeping radiant heat off the bulkhead the turbocharger sits against.

Premium T304 Stainless Steel
High-grade, corrosion-resistant material built to withstand the exhaust gas temperatures a tuned M139 produces.

Polished Connecting Pipe
The second section is a mandrel-bent polished pipe with a braided flex joint, absorbing engine movement so the turbo flange is never stressed.

Cleaner Tone Than Catless
The catalyst takes the hard rasp out of the note, which is the difference between a car you still enjoy on a long drive and one you do not.

Direct Bolt-On Fitment
Mounts to the factory turbo flange and mid section using the original brackets and hangers, with no cutting or fabrication required.

Performance Benefits (When Tuned)

• Increases of 25-35 HP and 40-60 Nm of torque

• Faster turbo spool and sharper throttle response

• Deeper exhaust note without the rasp and drone of a catless pipe

• Far less likely to trigger a check engine light than a catless downpipe

Vehicle Fitment

• Mercedes-AMG A45 / A45 S - W177 (2019-2025)

• Mercedes-AMG CLA45 / CLA45 S - C118 (2019-2025)

• Mercedes-AMG GLA45 S - H247 (2020-2025)

• 2.0L Turbocharged M139 Engine

M139 Only - This Will Not Fit an Earlier A45

The M139 turns the cylinder head around compared with the M133 that came before it. The intake sits at the front and the exhaust side faces the bulkhead, so the turbocharger is mounted at the back of the engine rather than the front. That is why the M139 makes so much more power from the same capacity, and it is also why the exhaust hardware is completely different.

This downpipe fits the W177, C118 and H247 cars only. If you have a W176 A45 or C117 CLA45, that is the M133 and it takes our W176/C117 downpipe instead. The two are not interchangeable in either direction.

Please Note

A high-flow sports catalytic converter is not a factory replacement part. Emissions hardware is regulated and the requirements vary between states, so please check your local regulations before purchasing or installing. An ECU tune is recommended to realise the full benefit of the part, and professional installation is recommended.

Why Choose Proven Performance Parts

We specialise in high-performance parts for European vehicles — Volkswagen GTI & R models, Audi S/RS platforms, BMW M cars and Mercedes-AMG. Every product we offer is carefully selected for its quality, fitment, and real-world performance — tested by enthusiasts, for enthusiasts.