Tuning engines in basically
illeagal in Sweden, especially on newer cars which have complete car approval (
"helbilsgodkända").
Cars from 1998 and later have this approval.
Look for the code T14A, T14D or T12Di in your registration documentation (
"registreringsbevis" ).
The approved exhaust level for
your car must be achieved at the annual government controled test
("bilprovningen").
However, some types of tuning would in reality be very difficult to discover and
exhaust values can be manipulated by adding additives to your petrol.