The GT3 has never gone head to head with Viper. The closest things we can examine are the lap times at Hockenheim, where the GT3 laps in 1:14.9. This is identical to the 385-hp Corvette Z06. Even without ABS brakes, the Viper has beaten that Z06 not once but TWICE in head to head track tests conducted by edmunds.com and Car & Driver. And it won by whole seconds, not fractions of a second. Some lap times from Thunderhill Park: Porsche GT2: 1:59's Viper GTS ACR: 2:04's Z06 (385 hp): 2:08.39 996 TT: 2:10.73 I don't expect that the GT3 would do much better than the 996 TT, if at all. My guess is that the Viper would beat it. If you're talking about straightline acceleration, the Viper has it in the hat.