VW stated that the 1001HP thing was a marketing gimmick as it sounded better. The Euro version has 987 SAE HP (1001PS) and the US had 1001 SAE HP, but the project director said they have the same engine - so I'm not sure what is going on.
Nonetheless, all the engines being made make between 1020 and 1040 HP, to ensure that the 1001HP is reached. A quite search on Veyron and 1020 has a lot of quotes about it.
200mph+ is a very challenging thing to do. There are very few cars that actually go that fast, and those than do have a lot of care and consideration go into them. You need a lot of downforce, and the car needs to remain stable.
The Viper has a slightly sub-200mph top speed in normal trim. Pushing it another 50mph without significantly changing the body of the car would be very difficult.
Nonetheless, a 250mph car will be much faster getting to 200mph than a 210mph car.