I broke 140 on the Speedo the other day "racing" that Viper. Of course the speedo is highly inaccurate at that speed, but the car was very solid.
Also there was NO-ONE on the road except me and the Viper. No one should be going that fast with other cars on the road... it's one thing to risk your own life, it's another to risk other's lives.
Keep it safe! And if ya really have the need for speed, take it off the highway and onto the track!