Black spots on stainless exhaust headers

[mspratz]

There are dark patches and spots all over the polished stainless steel exhaust headers of my 2024 R1250RS, which has done just over 11,000 miles. I initially thought it was rust and took it to the dealer to talk about a warranty claim. The dealer says it is something thrown up from the road, possibly road tar. They initially suggested using 0000 (superfine) steel wool. I spent 10 minutes rubbing away at one of the spots with it, but it did nothing, which at least seems to indicate it is not rust. The black stuff is so hard it is like a ceramic coating on the stainless. 
The dealer then suggested Simichrome Polish, which is $17 for a small 1.7 oz tube. It just arrived from Amazon, but I haven't tried it yet. I'll post an update later once I've tried it.
Has anyone else had a similar issue and succeeded in getting the marks off? If so, how?
   
   
   
   
   

[Grumpy Goat]

I showed these photos to a materials engineer in our office and the first thing he said is that it looks like an acid attack of some sort underneath the chromed outer layer. I thought similarly, but I was thinking more like rust in the alloyed metal used in the headers. He said that he'll look into it a bit more but since I won't see him till next year who knows when we might have more from him.