It's busy. If you're taking the mustang, dont get caught cruising too long or your leg will be dead the next day. I went in my old mustang once and driving 6 hours in stop and go traffic with a stage 3+ clutch killed me.
downhill with a tail wind
Plenty of people here claiming to hit that mark:
http://mustangforums.com/forum/4-6l-1996-2004-modular-mustang/93021-1998-gt-top-speed.html
Would take forever though