Since it is not isolated to one cylinder I would expect the turbo. There should be evidence of a heavy leakage going into the intake from the tubo. You want to verify this before rebuilding the tubo. I think it will be there myself.
Cheaper and easier than having a bad head gasket if thats it. Especially if you repair it yourself. Those exhaust ports all look very wet to me. Pretty good pictures by you help a lot as well.