I've read that chrome will typically start blueing at around 400-450 degrees.
I would bet that at the header, the pipe would get around 350-450 depending on ambient temp, etc.
I have an IR temp gun, but I don't plan on riding in the next month. Maybe I'll go let it idle for 10 minutes. I would bet 300 degrees after 10 minute idle.
on the heatshields, I would bet they're in the 100-140 degree range.