This whole thing has tremendous ramifications for most European owners. If I understand correctly all modifications in Germany require TUV approval. In Italy just changing the tyre size requires a "letter of no objection" from the factory and an inspection. If this is not available a complicated system requiring expensive engineers certificates and inspection is required. The other alternative is a later CoC and homologation for the same type of car.
I believe these problems dictated no left hand drive versions of the Plus 4 SS. Those that have been registered in Europe are registered as standard Plus 4 cars and the conversions to LHD were done by the dealers.
I hope these issues get sorted out for the European owners.