I'm looking to finish the exhaust on my OM603 powered S123. I don't have a good reference for the stock exhaust diameter.

Looking on this forum I've found references to a 2.5" and a 3" exhaust.

I have a lead on a stock downpipe from an 87 300TD and it looks like it will fit. But I still need to have the rest of the exhaust fabricated.

I'm looking at having one of these resonators put in.

https://www.borla.com/products/universal-resonators/

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Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

Straight pipe it. Mufflers, resonators etc make no difference on the turbo om603.

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CENSORED due to not family friendly words

Measuring my spare exhaust from my old 300SDL, I get 60mm or 2.38". 2.5" is probably close enough.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

straight pipes on 603's drone and sound terrible at anything under 3k rpm.

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Allen Kroliczek
Oak Grove Autosport | Oak Grove Autosport
01 G500, 82 300TD, quite a few more.....

I'm not sure what happened to the first version of this thread. The correct diameter is 60.5mm, roughly 2 3/8" ID.

Attached Thumbnails

 

I agree. I have a thrush hush or something of that nature on a 3" exhaust and it's barely louder than stock. Without it, it sounds terrible. Also if you go custom make sure the mounts are good and nothing is touching the body because a w126 resonates EVERYTHING

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Dan
2005 E320 CDI - 246k
1987 300SDL TD05-16g, Herlevi pump, Elbe manifold, 2.47 LSD - 213k
Past: 1987 300D - 264k

No. I'm not interested in a drone of any sort.

I removed the muffler on my 84 300D Daily because of rust and put a straight pipe in its place. It's not incredibly loud, but its got a drone at speeds that I'm not interested in replicating.

__________________
Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

Thank you.

__________________
Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

I'll probably reuse the stock mounting point and the same style of rubber hangers.

__________________
Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

Maybe in an NA engine but certainly not on an om603 turbo. I drove mine for a month with just a down pipe while I was still ironing out the .971 head and exhaust manifold swap. Didn't drone at all. T3 turbo does all the muffling you'll ever need. Eventually I had the exhaust reinstalled (.961 and .971 manifolds dump the exhaust at different angles requiring some welding) and there was no noise difference what so ever.

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CENSORED due to not family friendly words

Looks like every other individual posting with experience on the matter contradicted your own. Oh well.

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Allen Kroliczek
Oak Grove Autosport | Oak Grove Autosport
01 G500, 82 300TD, quite a few more.....

OP

Look into Aero Turbine mufflers/resonators, they're all straight through designs and the ceramic packing is excellent. I've not had one blow through with high EGT's.

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Allen Kroliczek
Oak Grove Autosport | Oak Grove Autosport
01 G500, 82 300TD, quite a few more.....

I don't know if it matters but all of my muffler-less experience was with a 3" exhaust and Hx30 / S200/ TD05 but I don't think it really makes much difference. Maybe a t3 and stock exhaust provide more sound control. I still wouldn't take the chance, there's hardly any benefit performance wise as long as you have a good flowing muffler or resonator. My logic was a bigger pipe with a slight restriction still flows more than a stock pipe with no restriction. On my SDL some of the bends were as small as 2" on the stock pipe.

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Dan
2005 E320 CDI - 246k
1987 300SDL TD05-16g, Herlevi pump, Elbe manifold, 2.47 LSD - 213k
Past: 1987 300D - 264k

I'd like to see who else drove an an OM603/T3 with just a downpipe for a month and 2000 miles. Even tested it with at various speeds with a DB meter. There's zero difference.


Anybody?

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CENSORED due to not family friendly words

I have the 603 with a stock downpipe and a mockup of 2.5 tube right now.

It sounds like crap.

Why would I want to continue like that for any longer than I have to?

__________________
Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]