Hi Oli,
The official max. speed of a stock GTS is in the range of 290km/h (181mph) and 295km/h (185mph). Depending on the magazine that prints the test...
So...finding the answer to your question is not easy, driving a bone stock GTS ...
But FYI:
Auto, Motor & Sport (a famous german car mag) did a test in 1997:
They compared the following - bone stock - cars:
- Aston Martin Vantage; supercharged V8; 557hp.
- Ferrari 550 Maranello; V12; 485hp.
- Corvette C5 Coupe; V8 - LS1; 344hp; (autom. Transmission).
- Viper GTS; V10; 455hp
Acceleration times from 0 - 250km/h (0-156mph):
- Aston : 29,2 sec.
- Maranello : 23,8 sec.
- Vette C5 : 43,9 sec. (..yep..thats Four-three-point-nine; hey ist an auto-trans.)
- Viper GTS : 22,5 sec.
Not bad numbers for the Viper, no?!
If my memory serves me right, there was a test where they compared the SL55 among others from 0 - 300km/h and the SL55 was faster than the Porsche Turbo and faster than the 550 Maranello..

Everyone there was supprised by the SL55's acceleration times!
So you got a pretty fast car there! Congrats.
...und an der Ampel, nach der Autobahnabfahrt, stihlvoll das Dach öffnen, hat schon was....
Gruss aus der Schweiz