I'm pretty sure you cant legally register a single turbo in Sweden very easily. Even Armin put stock twins in his car for MOT/registration time. I'd make sure on Swedish Supraforum
It was the same in Finland before, not possible without an expensive (1500€) rolling road emission test and no warranty to pass it, and it was 1500€ per try. Gladly the law just changed a year ago and we now can legally single turbo a Supra with a simple emission test done at the MOT station and dyno the car with less than 20% raised power from stock. Cars to be able to do this needs to be Euro1 emission grade, so usually under year 2000.
So before we just put the stock twins and IC back or find a friendly MOT guy and pay him a little extra to pass the test
Even if you would get an emission proof from Toyota or Tüv/Dekra, its for a stock car and not a single turbo modified one. So it will not help you anything. Only way is to get your own car tested and it will be expensive.