These little fellers arrived all the way from Italy and this afternoon I fitted them. They're 87mm across and should hopefully go in the tweeter location. The key thing is their depth. They're a mere 46mm in total height! You have to modify the cardboard surround slightly when mounting them to the underside of the speaker cover and "bend" the speaker terminals a little.
The sound I now get is impressive. I feel I'm in the middle of the sound stage rather than near the front with all the audio in the rear. Happy days!
My setup using all OEM wiring:
Tweeter Location: Hertz ECX-87 (60W). 2-way
Doors: Infinity Reference 6522i (60W) 2-way
Parcel Shelf: Infinity Reference 9623i (100W) 3-way
Radio: Kenwood KDC-DAB4557U