When i got may S2 Stagea with 85000km had some turbo whine, i didnt care as i got it cheap so i didnt mind if i needed to put a turbo on it. I have had plenty of turbo cars before and family races turbo cars. The whine was not really that bad was the same as a old VL turbo my old man use to race back in the 90's
After a month of owning it i wanted the change the timming belt and just service every thing on the car as i use it to tow my race car and need it reliable, i have read on the forums before its common the turbo gaskets leak so i changed it, when i took it out there was a very small hair line crack in the turbo gasket. Since that day i have no more whine at all, did nothing else to the car but timming belt turbo gaskets and oil filters, i even reused the air filter as it was so clean when i bought it.
Just somthing you could check if you have any concerns with turbo whine.