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M256 Catless Downpipe – E53 CLS53 GT53 GT43 GLE53 GLE450 CLS450 S500 (2017–2020) 3.0L I6
M256 Catless Downpipe – E53 CLS53 GT53 GT43 GLE53 GLE450 CLS450 S500 (2017–2020) 3.0L I6
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A heat-shielded catless downpipe for the Mercedes M256 3.0L turbocharged inline-six, fitting the AMG 53 cars and the non-AMG models that share the engine — E53, CLS53, GT53, GT43, GLE53, GLE450, CLS450 and S500. It replaces the factory catalytic converter to cut exhaust restriction, giving faster turbo spool, sharper throttle response and a richer exhaust note. 3.5″ inlet tapering to 3.0″ (both outside diameter), 1.5mm wall, with an integrated flex section to reduce vibration and thermal shielding built in rather than sold as an add-on.
Key Features & Benefits
- 3.5″ Tapering To 3.0″, 1.5mm Wall — both figures are outside diameter, sized to what the M256 actually flows. The taper accelerates exhaust gas through the section rather than letting it stall in an oversized pipe, which is what protects mid-range torque and turbo response
- Integrated Flex Section — absorbs engine movement and reduces vibration passed into the rest of the exhaust, which matters on a longitudinal inline-six sitting in everything from a sedan to a GLE
- Integrated Heat Shielding — high-temperature shields cut radiant heat coming off the pipe into the engine bay, protecting nearby wiring, sensors and plastic components. Not a separate add-on and not an option to select
- Full Catless Design, Direct Bolt-On — maximum exhaust flow with no cutting or fabrication, across both AMG and non-AMG M256 cars
You Will Need Tuning — Your Build Date Decides Which Route
The downpipe is the hardware half. Tuning is what lets the ECU use the extra flow and resolves the fault codes a catless setup will otherwise set. On the M256 there are two routes.
Built before roughly mid-2020: your Bosch MG1CP002 ECU is very likely flashable directly, and a custom calibration gives the most headroom. Custom M256 ECU tune →
Built from roughly mid-2020 onward: the ECU ships with factory tuning protection, so flashing means removing it and mailing it out for a bench unlock first. The JB4 skips all of that — it never writes to the ECU, so the lock does not apply. Installs in about an hour and comes off without a trace. JB4 plug-and-play tuner →
Your build date is printed on the driver's door jamb sticker — check it before choosing a route.
Compatibility
| Chassis | Years | Models |
|---|---|---|
| W213 — 4MATIC | 2018–2020 | E53 AMG |
| C257 — 4MATIC | 2018–2020 | CLS53 AMG |
| X290 — 4MATIC | 2019–2020 | AMG GT53 4-Door Coupe |
| X290 — 4MATIC | 2019–2020 | AMG GT43 4-Door Coupe |
| V167 — 4MATIC | 2020 | GLE53 AMG |
| C257 Coupe | 2018–2020 | CLS450 |
| V167 Base | 2019–2020 | GLE450 |
| W222 Base | 2017–2020 | S500 |
All fitments above use the turbocharged 3.0L inline-six (M256). If your car is on that list, this bolts straight on with no cutting or fabrication.
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
Does this fit non-AMG cars like the S500 or GLE450?
Yes. The GLE450, CLS450, and S500 use the same M256 3.0L turbo inline-six as the AMG 53 models. If your car has the M256, this is the right downpipe.
Why 3.5″ tapering to 3.0″ and not one straight diameter?
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 accelerates gas through the section instead of letting it stall in an oversized pipe.
My car is newer — can I still tune it?
Yes. Cars built from roughly mid-2020 onward have factory tuning protection on the ECU, which a flash tune cannot write to without a mail-in bench unlock. The JB4 piggyback avoids that entirely — it works alongside the factory ECU rather than replacing its software, so the lock does not apply. Your build date on the driver's door jamb sticker tells you which route applies.
Will I get a check engine light?
Likely, on an untuned car. Removing the cat means the downstream O₂ sensor reads differently than the ECU expects. Tuning resolves it properly — we do not recommend defeat devices.
Is the heat shielding included?
Yes — the thermal shields are integrated, not a separate add-on. Their job is keeping radiant heat off the surrounding engine bay, not changing how the turbo spools.
Are these street legal?
No — fully catless, intended for off-road and competition use only.
Is there a warranty?
Yes — a 12-month structural warranty, with guaranteed fitment on every model listed above.
