I was looking at
this (unfortunate) thread and at around 0.57s you can see the brembo rotor, which looks considerably different than the US spec rotor that you can see in various photos.
Then I pulled up the european catalog from
here and confirmed what I was seeing: the specs for the front 380 kit is 380mm x 32mm rotor with the M caliper. From race technologies (
here) the US spec 380 kit has a 380mm x 34mm rotor with the N caliper that accepts a 57.5mm swept area pad vs the M caliper which has a 52.5mm swept area (
source) which is smaller.
Also the M3 GTS spec rotors look similar, which means that the GTS probably has the M caliper instead of the bigger N caliper. What further reinforces this, is the fact that the GTS front rotor is 378mmx32mm. Also it looks like only the 380mmx32mm kit seems to be TÜV approved. See european catalog link above for the X in the TÜV column.
Also, if you look at the european catalog, 380mmx34mm sized kits with the wider N caliper are indicated for the E60 M5 and E82 1M in Europe.
All other configurations have the same dimensions.
Just FYI, since I am waiting around currently. But it would be interesting if any knowledgable vendor could chime in.