No. There are plenty of slower stock GTs. I'd imagine you could take 79-84 GTs, convertible or not, pretty easily. 96-98 4.6L GT convertibles are also slower than you.
Congratulations. You do not have the slowest type of GT.
Well, no. But, its still slow. Like mid/high 15's slow if its in good condition. I wouldnt be surprised if it ran 16's because it needed a tune/had a worn tranny.
no way, especially the 87-93's because they weigh much less. Dont fear tho, due to the fact that you own a mustang, and it has limitless aftermarket potential, you wont be slow for long providing you have some cash