As far as I know, the Government Statuatory Warranty is three months with "all" cars sold through a car yard.My friend actually went through something similar with another car yard when he bought his Soarer.
The situation was that the clutch died 4 days after purchase about 150KM travelled, when ringing the caryard in question before even seeing the car the guy said that my mate must have destroyed the clutch and that it wasn't covered by the warranty anyway.
One quick phone call to Fair Trading and Lo and Behold it seems that Car Yards do not have the choice on what is covered by warranty nor is there a limit for "older cars" of one month.
One threatening phonecall from a lawyer later, clutch was changed under warranty.
If I was your mate I wouldn't be taking the line of bullshit fed to him by this particular caryard.
They have already made shitloads of money out of this car by the looks of what they charged him for it. So they can afford to fix the stuffed Turbo. The only thing that he may have to worry about is that the Boost Controller has been set to 1 Bar and they may try to say that your friend set it too high and that is why it is stuffed. I would have the boost controller disabled and say that it never worked so they can't shift the blame to him.
Hope this has been of some help and good luck