I have added 20 registration spots. You will see more registrations than 100 probably, but there are people who are not bringing their cars. You are welcome to attend without your GT but my advice is that the event is significantly less fun without a GT, and you will think to yourself "I should have brought my GT." Additionally, rental cars or non-Ford GT cars will not be part of the concours.
Same with me after buying car right before Rally 7. Did not really know what to expect and didn't take my car. Hilo Dave introduced himself and aksed if I brought my car. When I said no he called me a pussy! Never made that mistake again and miss seeing Dave.