There is a huge difference between the factory Bilstein‘s and the aftermarket ones. Totally different division. My daughter put them onto two of her Toyota’s. 5100 or 6100 series. And she loves them. And the 8112 DSA + are something else altogether. Yes, expensive but they save the cost of having to replace everything else. Unfortunately none of this stuff is inexpensive.
Well, that's my point, I don't think there is a difference. I've put Bilsteins on four of my vehicles dating back to 1999. The last set was on my E90 in 2017. The dampers did not hold up well and got harsh around 40,000 miles in. Buy 70,000 miles I had to replace them. The paint was not robustly applied and the shock bodies became corroded early on. As compared to the set I have on my wife's Z3 that I put on in 2009, which now have about 70,000 miles on them and they still dampen perfectly 16 years later.
With a name like Bilstein, there should be no quality difference between the aftermarket product and the versions used as factory production parts. The product should not fail like it did.
No salt tram towers were harmed in the making of this post...