http://www.z28.com/forum/showthread.php?t=118397
Here. Turns out that there was a 105 Mph govenor on some Z28's with differant tire sizes. And in December 1993 Car and Driver tested a '94 Z28 against a '94 Mustang (blew it away btw) and they reached a top speed of 156 Mph in a 6 speed.