Just something to note.
Toponline.com glass top kit comes with tall the necessary wiring to hook up the defroster.
Convertibletops.com also sells the Robbin glass top kit for less but I don't know if it includes the defroster wiring.
http://www.convertibletops.com/porsche.html
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-99' Zenith Blue 5-spd...didn't agree with a center divider on the freeway
-01' S Orient Red Metallic 6-spd...money pit...sold to buy a house