Best way to ship heavy speakers to Norway.

Palet and put the factory box inside a foam filled outer box.

Adcom Worldwide did a nice job for me locally and I know they ship anywhere. Wilson uses them, which is why I picked them on a dealers recommendation, so they are well versed in dealing with large, heavy and expensive speakers.

Strap them to a wooden palet. It is a must IMO. This way I have shipped Peak Consult speakers @ 300kg to Japan. Arrived safe and sound.

I assume you have the OE boxes for the speakers.