E53 catless downpipe
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From: Taiwan
GLC43, X P100D, S P100D, CT200H
Sounds great but i thought after the car went catless, that muffled howl sound would be gone. Is that the result of the OPF? Where is the OPF and can the OPF be removed?
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From: Mississauga, Toronto
GTS AMG
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From: Taiwan
GLC43, X P100D, S P100D, CT200H
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GTS AMG
I didnt notice anything abnormal except the size of the cats was huge. There’s nothing else in the exhaust except the muffler
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From: Taiwan
GLC43, X P100D, S P100D, CT200H
It stands for Otto Particulate Filter and it is somewhere in the exhaust system.
I know the 2019 C43/63 has it, so very very likely the 53s as well.
The 367hp C43 in 2017-2018 had .9bar(12psi max boost) stock. It was heavily advertised that the 2019 390hp C43 had 1.1bar (16psi max boost) stock. But people who tune their 43s know that 16psi is closer to 430bhp rather than 390bhp. So many wondered if the difference in hp is due to the OPF.
The 2017/2018s and the 2019 sound wildly different.
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cls53
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From: Twin Cities
Too many to list
Benefits:
-lighter
-shinier
-more free flow
-minimal power gain
-louder exhaust note---this could be a con too
Cons:
-smellier
-CEL so a tune is necessary
-won't pass emission even if tune got rid of CEL
-a pita to install
-cost
-will void emissions warranty or the entire b2b/extended warranty if stealer don't like you
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Joined: Feb 2016
Posts: 697
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From: Taiwan
GLC43, X P100D, S P100D, CT200H
- More Power
- Will add a bark/rasp/louder characteristic to your exhaust note. Catless exhaust have a distinctive sound compared to catted exhausts
- It is possible to not have CEL with catless/High-Flow cats but even if the CEL doesnt trigger today it might trigger next week but it might also just disappear again after a few days/hours.
Cons:
- Smells like gas
- Will obviously void your exhaust warranty.
- Has a higher chance of voiding your entire engine warranty (compared to just changing midpips and muffler) since the downpipes are directly adjacent to the engine.
- Even if the CEL doesnt trigger, Benz will immediately see your shiny aftermarket downpipes when they perform your oil change or service. It is very very obvious.
Realistically though most people just do it for sound and it doesnt cause any problems. Any problems the downpipes do cause are related to itself only. Like if the downpipes rattle or crack. They are unlikely to cause any peripheral or collateral problems.
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GTS AMG
I can’t say for sure on this car because customer didn’t want before and after dyno and he also didn’t want cel delete however catless downpipes have huge power gains on turbo cars and besides a tune it is the best mod for power and sound.
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From: RI
2018 C43 AMG Coupé, 2020 AMG GT53
Looks like cat and the GPF/OPF are two separate parts. I wonder if removing the GPF/OPF from the OEM downpipe would not trigger a CEL. Another idea is to wrap the downstream o2 sensor in the catalytic material to fool the system. From what I read the GPF/OPF is killing the sound (high pitch crackles, burbles, etc.) much more than the Cat. The picture isn't clear what's the OEM P/N of the downpipes? looks like A 250 140 02 08 but It's too blurry. I might buy one and mod it for a GT53. I think modding the OEM would be good for people who don't want a cel fix with a ECU tune but want louder exhaust while keeping the air cleanish 
Last edited by C43amg4matic; Sep 30, 2019 at 07:51 PM. Reason: found a diagram P/N: A 256 140 02 08 the GPF is downstream
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2019 AMG GT53
My 2019 AMG GT53 is currently in the shop getting a catless downpipe and stage 2 eurocharged tune installed. Will post about it when done since there is not much info out there yet. Downpipe is from Brondex Performance.
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From: Mississauga, Toronto
GTS AMG
sounds good! We have updated our customers tune with o2 cel delete and burble, also advanced the power in the tune. He is super happy but still won’t pony up for a before and after dyno for us to post up unfortunately.
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C257 CLS 53 AMG & W211 E55 AMG
I just ordered a catless downpipe for my 2020 CLS 53 and was wondering what tune do you offer? Also where is your shop located?
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C257 CLS 53 AMG & W211 E55 AMG
Hey man Im wondering where can I find a Stage 2 Eurocharged tune that you mentioned for your GT53? I also ordered a Brondex Downpipe but for some reason I'm only able to find a Stage 1 Eurocharged Tune..
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Not to rain on your parade. Did you buy that downpipe? That downpipe is not good. My catted downpipe is 3.5 inches all the way to the mid pipe. To choke down the downpipe means to change sound and performance. The outlet of the turbo is 3.5 inches. I went with a free flow cat downpipe that does past inspection and does not smell like gas. The filter is in the old downpipe. It's a 2 parts catalytic converter system. The Tune cleans up the check engine light and free up more power. You don't really feel the full effects of the power until you tune the TCU and CPC. The TCU and CPC controls toque and horsepower. Tuners were tuning the ecu to tricking the TCU and CPC into increasing the horsepower. This cause transmission slip and after the CPC operating system figured it out it decrease the power back close to stock to save the transmission.
Last edited by Gt53; Nov 3, 2025 at 01:40 AM. Reason: change words
