G-pop sells a rebuild kit for the VNT 15. I have no idea where it is made. They can tell you that.
Even with a brand new "Made anywhere besides China" kit, you are talking about a device that turns more than 150,000 RPMs..... some say up to 200,000 RPMs. So, keeping the Turbine and Impeller "relationship" perfect (as in precise marking), is the big challenge. If they are not put back exactly as they were, the unit will be out of balance! Everything else inside the VNT 15 is quite simple!
I've stripped them to the bottom, cleaned and re-assembled! No complaints yet! Emphasis is on "yet."
Talking just a clean-up, not a rebuild!