R129 Replacing Exhaust any idea's 1990 model

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R129 Replacing Exhaust any idea's 1990 model

Post by probids » Thu 18 Sep, 2014 3:21 am

I am looking at replacing exhaust on a 1990 SL500 UK import now in South Australia.

I have just spent a few hours looking online but most info is outdated and I was wondering if any members had any suggestions on which way to go on a dual system that has a bit of grunt.

Any feedback would be appreicated.
1986 300SE - sadly gone
1979 450SEL - gone but not forgotten
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R129 Replacing Exhaust any idea's 1990 model

Post by McGavin » Thu 18 Sep, 2014 8:25 am

By coincidence I saw this last night,
The positioning of the crossover / high flow cat / resonaters , whatever comes first and acts as a collector ,appears to be the most crucial aspect of tuning an exhaust for optimal scavenging /performance in the desired rev range, next is a muffler / mufflers that's flow exceeds the pipe. Surprisingly least crucial, within reason is pipe size.
Did a lot of reading last night, all just theory though.
Last edited by McGavin on Thu 18 Sep, 2014 4:33 pm, edited 1 time in total.

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Re: R129 Replacing Exhaust any idea's 1990 model

Post by AMG » Thu 18 Sep, 2014 10:03 am

The only solution to your problem is to either buy an aftermarket off-the-shelf performance item (generic, not always an improvement over OE) or have it fabricated.

Don't waste your time with exhaust shops who just fit mufflers - like midas etc.

You need to find a shop who specifically does mandrel bends (that's a pull-through mandrel not a cheap-ass die bender)

the 'new' stainless steel is 404 - it's replacing 304 for exhausts. If you have money and a capable expert welder, then inconel 625 is what you ideally want, in a twin 2.5" pipe arrangement.

beware you will need flanges or slip-joints on the catalytic converters (you will need 2 for a performance exhaust - or dare I say it, accidentally forget to install them) and the cats need to be high-flow 200 cell. a 600cell is too restrictive, hence the twin 200 cell requirement.

Mufflers - Magnaflow are very nice. I have a set on my 560 at the moment. They give a very nice note. But... you need to carefully examine the space the muffler will occupy before ordering them, as well as the entry / exit points. Magnaflow have various 'grades', and it's advised to err on the expensive side rather than the cheaper ones.

You will need a centre muffler / x-pipe / cherry bomb / hotdog to reduce the cabin drone at low rpm's, or it will be come annoying. I can attest to this.

However you will only need 2 mufflers - a centre box and a rear, if you want 'good sound'

suggest you ask locally for the 'best' guy - and do yourself a favour and ask people who have actually had work done - and I don't mean replacement systems, I mean a fully fabricated flanged setup.

And believe me when I say, a penny saved here, is a dollar you will have to spend fixing it up in a very short space of time.
1987 560SL 4sp. auto Signalrot "Stella"
1987 190E 2.3-16 5sp. man. Blauschwarz "Hermann"
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1972 350SLC Astralsilber "Lurch" - now in the loving care of Craig B
1989 2.5-16 Blauschwarz 4sp. auto (parted) formerly owned by Derek/Hasan.
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Re: R129 Replacing Exhaust any idea's 1990 model

Post by film » Tue 23 Sep, 2014 6:13 pm

I can recommend Mille Miglia http://millemiglia.com.au/contact.php for mufflers & bends, made in Bathurst & have always had decent design for the muffler centres which is similar to that now used on the new McLarens. Also the muffler packing is a decent quality, takes much higher temperatures that most others.

Inconel? - lay off the strudel for a month & put 5 litres less in the fuel tank.

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