Upon taking a closer look at my turbine housing, I found this tiny line, which I believe to be a crack. I doubt it's a gouge, but maybe it is? There also are scratches nearby, and a rather large nick above the suspected crack. Turbine wheel is in excellent condition. What's my plan moving forward?

 

I see no scratches, gouges, or cracks. I see a raw cast surface.

 

Interesting! Maybe I’m too worked up about it, but I would like to hear more opinions. It probably doesn’t need pointing out but just in case, these two areas are the ones I’m most concerned about.

 

Smooth those out with a die grinder maybe.

 

Both of those look totally normal. Hit them with a dremel or die grinder if it bugs you. Or heat the area with a torch and see if it spreads. Then you would know for sure if its a crack or just casting. My vote is that its just casting.