Issues trying to find the correct exhaust/header system for my bike

[Enforced_Leo44]

Hi everyone, first time posting on this forum

I recently bought a 1983 R100RS (that has been scramblerized) and I need to find a new exhaust because the original ones are gone for good, rotten and dented (and also the previous owner cut them short to fit some straight "cafe style" mufflers)

But I can't seem to find a definitive answer to what kind of exhuast I should get, the only thing I know for sure is that the OD is 38mm

If I search on the official BMW spare parts shop, searching for model and year of the bike, 3 different exhaust system pop up, one is 40mm OD with 1 crossover pipe, one is 38mm OD with 1 crossover pipe and the last one is 38mm OD with 2 crossover pipes

So, surely it's not the 40mm OD one, but how should I choose between the single and dual crossover types? are they interchangeable (fitting wise that is, I know that performace may differ if I install one over the other but I don't really care about fine performance differences) ?

[Rob Frankham]

A '83 bike will have two crossovers. They are pretty much interchangeable but you can't mix them (obviously). There will be a slight performance difference but not really noticeable.

Rob

[Zombie Master]

Airheads are usually quite muffled. But the boxer engine can really sound beautiful with the right exhaust, and it doesn't have to be loud.
I've been thinking of a set like this.

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[Enforced_Leo44]

A '83 bike will have two crossovers. They are pretty much interchangeable but you can't mix them (obviously). There will be a slight performance difference but not really noticeable.

Rob

Found a nice pair of chrome NOS dual crossover headers, now I just have to fabricate the crossover pipes but that should be easy

Now I'll have to find a fitting muffler for the build, something minimal but still retro/vintage