My tweeters are scheduled to arrive today.
Finally did a bit of research and reminded myself that what I wanted was Piezoelectric (not electrostatic, as I indicated in an earlier post) tweeters and was able to locate a
good app note from CTS for some
effective small tweeters, model #KSN1193A. These will not require cross-overs, only a small resistor to protect the amp from any possibility of damage at high power/high frequencies (the Porsche/Becker head unit shouldn't generate even close to enough power to cause this, but just to be safe...).
Hope to get these installed this weekend, will reply with the set up and results when I'm done.