1990 Corvette ZR1 like mentioned above...
ran 12's I think??? all I know is that the GN was never touched in the 80's period. they ran high 13's stock and the GNX ran 13.3
just imagine if the rumor about the twin turbo 4.5L V6 2003 GN concept car was true...it would definitely dethrone the Viper for america's fastest car title