BenzUnited Parts
M133 Catless Downpipe for Mercedes CLA45 / GLA45 AMG (2014–2019)
M133 Catless Downpipe for Mercedes CLA45 / GLA45 AMG (2014–2019)
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The factory downpipe is a major restriction on the Mercedes CLA45 AMG (C117) and GLA45 AMG (X156) with the M133 2.0L turbo. This high-flow catless downpipe removes that bottleneck for noticeably quicker turbo spool, stronger mid-range torque, sharper throttle response and a much more aggressive exhaust note. Make up to +55 whp and +84 wtq when you pair with our dyno proven Stage 2 ECU tune.
Key Features & Benefits
- 304 Stainless, — Mandrel-Bent 3.5″ To 3.0″ size accelerates exhaust gas through the section, protecting mid-range torque and turbo response on the 2.0L M133.
- 8.5mm High-Tensile TIG Welding, CNC-Machined Flanges — the welded joints and flange faces are the two things that leak on a cheap downpipe. These are machined for OEM-style fitment and sealing
- Integrated Flex Section — braided outer shield over an interlock liner, absorbing the movement a transversely mounted engine puts into the exhaust instead of passing it down the system
- Direct Bolt-On — OEM-style V-band with correctly positioned O₂ sensor bungs. No cutting or modification; professional installation is recommended
Dyno Verified — 351 whp and 369 wtq on Stage 2
The full dyno pull video and graph are in the gallery above. Running this downpipe with our Stage 2 ECU tune, the car measured 351 whp and 369 wtq at the wheels — a gain of +55 whp and +84 wtq.
Complete the Stage 2 Build
This downpipe is the hardware half of a Stage 2 M133. The tune is what turns it loose — it lets the ECU take advantage of the extra flow, and it clears the check-engine light the catless design will otherwise set.
Compatibility
| Chassis | Years | Models |
|---|---|---|
| C117 Coupe | 2014–2019 | CLA45 AMG |
| X156 SUV | 2015–2019 | GLA45 AMG |
Warranty, Shipping & Returns
- 12-month structural warranty — covers welds, flanges, and structural integrity under normal street use
- Free U.S. shipping with tracking, shipped next business day from US stock
- 30-day returns — unused and in original packaging. See full return policy →
Frequently Asked Questions
Why 3.5″ tapering to 3.0″ on a 2.0L?
A downpipe sized past what the engine actually flows drops exhaust gas velocity, and velocity is what carries mid-range torque and turbo response. Each downpipe is sized to the engine it fits rather than to one number applied across every platform. The taper here is deliberate — it takes the large turbine outlet and accelerates gas through the section instead of letting it stall in an oversized pipe.
Will this throw a check engine light?
It can, yes. Running catless without ECU tuning will often trigger one. A tune clears it properly — we do not recommend defeat devices.
Is it street legal?
No. It removes the factory catalytic converter, holds no CARB Executive Order, and is not legal to install on a vehicle registered or operated on public roads in the United States. Off-road and competition use only — see the emissions notice at the top of this page.
Do I need to cut or modify anything?
No cutting. It's a direct bolt-on using the OEM-style V-band, with CNC-machined flanges and correctly positioned O₂ sensor bungs. Professional installation is recommended.
Does my car fit?
CLA45 AMG 2014–2019 and GLA45 AMG 2015–2019 with the M133 engine. The engine code is what decides fitment on this platform.
Is there a warranty?
Yes — a 12-month structural warranty, with guaranteed fitment on every model listed above.
Off-road Use Only. Not legal for use on emissions-controlled vehicles or public roads.
