Careful with the Mundorfs.
AMTs have a great wide dispersion, but their vertical dispersion suffers greatly.
They need to be aligned almost perfectly at ear height, vertically, or you will encounter the "on/off" effect when moving your head around.
It's one of the main knocks on AMT/Ribbons, and why, even though they exhibit exceptional tonality. micro-dynamics, transparency, and almost non-existent listening fatigue, they are used much less frequently.
I have them in my home theater towers, and absolutely love them, but not sure I want to do what it takes to get them to perform optimally in a car/auto environment - especially at their nearly $800-$1100.00 a pair price/cost.
Considering you're in Europe, consider a good berylium, like the BlieSMa T25B-6, Scan-Speak, or the SB acoustics beryliums as they are in the same league as the Mundorfs, sound amazing (close to or as good in my opinion, as the Mundorfs).
These are worthy options:
BLIESMA T25B-6, Beryllium 25mm (1in) Dome Tweeter. 94db, 6ohm, 68mm Faceplate
www.solen.ca
ScanSpeak Illuminator D3004/6040-00 Beryllium Dome Tweeter - Each. High-quality tweeter in stock. Crossover and system matching advice available.. Contact us.
www.madisoundspeakerstore.com
SB Acoustics SB29BNC-C000 29mm beryllium dome tweeter with protective grille. Technical specifications and documentation for speaker building.
www.madisoundspeakerstore.com
ScanSpeak Illuminator D3004/6040-10 Tweeter Beryllium Dome. The Illuminator tweeters continue on with the heritage of the renowned Revelator series. The large-roll surround and textile dome diaphragm provide a flat frequency response to above 30KHz with outstanding off-axis dispersion.
www.madisoundspeakerstore.com