I had my 2001 coupe on the Bonneville SaltFlats. HUd was reading 178 mph. rear was full of luggage.. Felt with out the luggage and passenger I could have gotten about 5 more mph out of it , as I was at about 5800 rpm in 5th. The only mods I have are Z06 clutch, Hurst shifter, and K&N air filter.
01 Speedway White/Black
Coupe, 6 speed, HUD, Hurst Shifter
2002 Z06 Flywheel assembly,
K&N Air filter
You will get different topspeed values depending on what C5 model (coupe, FRC, vert, auto, 6speed, axle ratio) you are clocking. I did some topspeed clocking on the german autobahn, here the results (all cars in stock condition):
'99 LS1 A4 coupe axle 3.15: 171mph
'99 LS1 FRC axle 3.42: 175mph
'01 LS1 vert 6sp axle 3.42: 173mph
'02 LS1 coupe 6sp axle 3.42: 177mph
I Hope that will help you.
(the values were metered by stop watch over one flying km, no wind, 20 degrees Celsius))
There had been an article some time back in "Corvette Fever"? about a guyin Texas somewhere that had taken his daily driver to an oval track and had run it up to 200mph. The speed had been verified because when you hit 200 the hud reads 00, not 200.
Some of the "Chicago Crew" (ZRDon) had talked about finding a stretch of road to do a top speed run but nothing ever materialized.
I'd have to worry that once I found out what top end was I'd want to get there any and every chance I got.