I love the Ford GT, but it by no means crushes the ZO6, or even beats it…
http://www.automobilemag.com/reviews/coupes/0511_z06_gt_viper/stats.html
Performance specs on page 4. Remember, the ZO6 has the worst tires by far and would be signifigantly faster around the track if it were equipped with the tires that the Viper/GT come with.