From what I understand, at least in the Golfs that are available in the US (not sure of the JSW), the TDI and GTI versions of the car are made in Germany (VIN# starts with a "W"), where as the 2.5L versions are made in Mexico.
Now I myself have traveled all over North America installing / training on CNC Machining equipment and to be honest, with the dozen or so trips I have done to Mexico I have yet to see any reason why the quality could be any less than that of the same part made in the US or anywhere else in the world.
We worked with GE / Toshiba in the US at their power generation plants machining turbine blades (Greenville, SC & Bangor, ME) and their sister plant in Cienega de Flores, MX and the facility in Mexico was much more efficient. More up time, more thru-put, and less quality issues. Now an argument could be made as to why it was the way it was (newer facility, newer equipment, non-union vs union, etc....) but that is how it was.
My father and uncle both retired from Chrysler, and my uncle was a plant manager at Mound Road Assembly (Detroit - this is where they build the current 1500 Ram and Durango) and at one point Chrysler had 3 truck plants assembling trucks, Detroit, St. Louis, and Hermosillo, Mexico. And for many years, the Hermosillo facility had the lowest number of issues with squeaks, rattles, etc....