No coating, I did polish them and I think that is why they look the way they do. If I put brakleen or carbclean on the rag they wiped right off. I just wiped them off with a shop rag for the picture.
It almost looks like there is an increase in pressure where the valve relief is, like its getting hotter there? Or maybe because the valve gets so close there is not enough room for fuel/soot to.stain in that spot? :dontknow:
Are you using a motorsports nozzle/tip or standard but exergy modified injector, i thought i counted 7 injection spots on those pistons? But cant tell...