this is from car and driver magazines test of an 800 hp viper.
notice the 1/4 mile time and mph with less hp than the viper in question in this thread.
2004 hennessey venom twin turbo viper
of the 5 runs
the average 1/4 mile time was 11.14 seconds
the average mph speed was 140.60
Run # 1 2 3 4 5
0-60 mph, sec 4.02/ 3.66 / 3.85 / 3.53 / 3.57/
0-100 mph, sec 7.08/ 6.63 / 6.95 / 6.50 / 6.53/
1/4-mile time ET, sec 11.37/ 11.09 / 11.31/ 10.96/ 11.01/
1/4-mile time TS, mph 138.80/ 140.70/ 139.20/ 142.50 142.20
Time to entrance of road course, sec 17.10 17.65 17.85 17.25 17.20
100-150, sec 10.61 7.50 7.71 DNF 6.90
150-0, feet 706.48 705.40 726.49 DNF 728.74
150-0, sec 6.55 6.58 6.84 DNF 6.80
Vmax, mph 157.30 150.90 150.70 144.80 150.90
Road-course time, sec 52.65 47.80 48.00 47.70 47.55
5-sec penalties 1 0 1 0 0
Official time*, sec 104.75 92.20 98.55 DNF 92.45
http://www.caranddriver.com/article.asp?article_id=8745§ion_id=15&page_number=3