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Those are completely different tensioners. Could be a really early N57 in that picture?
Looking into it a bit more, it seems the tensioner was updated multiple times.
My 30d is 09/2016 build date and had tensioner no. 11 31 8 576 201, which is not shown on RealOEM.
There is also a tensioner 11 31 8 586 699 which ended in May 2019.
The new tensioner 11 31 8 490 219 is May 2019 to present.
My old one and the new one are identical externally. Same piston length and spring strength. The only change is to the piston inside it.
I questioned myself how a tensioner could bring about so much improvement, but it did.
It always had a slightly wobbly idle when hot like it was running on 5.5 cylinders, which I could only feel if my leg was resting on the centre console, so it was very slight.
That is also gone now. The idle is rock steady and smooth.
It was always good from cold, so it stands to reason if the piston is bleeding off pressure when the oil heats up and thins out, it would cause a bit of chain slack.
You don't have to believe me. I am only reporting my findings. I have done 200 miles since fitting the new tensioner and it's still the same, so it wasn't a one off or placebo.
BMW updated the tensioner multiple times for a reason, and this post was merely a suggestion to change it regardless as it doesn't hurt to run the latest parts. If people get the same results as me, then great. If not, no harm done and it's peace of mind the chain is as taught as it can be.
Obviously proceed with caution at your own risk. I have also not seen any special mention of setting the crank to a specific angle before replacing it, so it would appear to be a safe swap.
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