I guess it's time for another Viper owner to chime in. First of all, I've had a variety of sports cars over the years, from old Alfas (still have a 73 Spider) to an RX7 twin turbo and a 98 E36 M3. I have recently become interested in Domestic muscle cars and my wife and I now own a 99 Viper GTS and 01 Z06.
I think Ilya sums up the Viper's strengths quite well. It is the most exciting car I have ever owned. It definitely has more power then the Z06 and pulls harder at 160 mph then the Vette does at 120 mph.
I have driven the Viper a few times at the track and believe that the Z06 would be close to the Viper in overall lap times. The Vette has more road feel, and is easier to tell how close you are to the limits of adhesion, but the Viper also handles quite well. It has lots of grip with minor under-steer.
The Viper is challenging to drive to it’s potential not because of any handling difficulties, but because it has such great high speed acceleration that it takes time for a ‘normal’ person to get used to it. I have lots of track days in a modded Z28 and the Viper is seriously faster. The only aspect of the stock Viper's performance that I think should be better are the brakes, although pad, fluid, and air deflectors help considerably.
As far as being fast at the track, driver skill and daring is a huge factor. I am easing into using the Viper as a track car, but definitely do not want to wreck the car. Taking the Viper to track days can be frustrating because other car owners seem desperate to 'beat a Viper'. The Viper is such a performance benchmark that people act like you should be setting lap records just because of the car
On the street, the Viper is nice and tight, and rides very well given the level of grip. It is loaded with cheap plastic, but that doesn't bother me. The only thing that really bugs me is the heat the side pipes pump into the car during the summer. The stereo isn’t too great, but that doesn’t bother me either - tire noise and exhaust drown it out anyway!
As far as a comparison to an NSX, I don’t really know because I’ve never driven an NSX, although every time I see an NSX on the street or track, I admire the car and think that I would truly enjoy owning one.
Oh well, so many cars, so little time…
Jim