Apparently some of out gti's don't come with this resistor.
Found this on another thread courtesy of maxitrol.
Not all models had it though, depending on the system installed. Eg. Climatronic, climatic etc
Mine has Climatronic (digital dual zone climate control) and doesn't have a resistor.
The resistor is a match box sized thing, located behind the glove box, with a green coating. It has a white plastic loom connector.