Do you mean one of these?
Its MK6 or Scirocco gps shark fin, never came on the MK5 the early cars without aerials and nav had a different gps aerial with just the gps inside, but these phones had two aerials in the rear hatch panel, the later cars then switched to a half bee sting half gps unit, and then Mk6 have as above which has gps, phone aerial, and aux heater signal integrated.
If the after market unit uses fakra gps plug then it would work but its worth considering that you need to keep the beesting aerial as well as the gps un-less you go for combined type.
