how many top-speed rings are there that the public can access?
even a stock TT can get up to 155 or so, a little faster if you remove the guv'nor. I doubt there are many roads or even race tracks where you could go faster than that.
The challenge is to get to that max *useful* speed faster. Even for 1/4 mile, you'd never see a 155 mph trap speed without some serious quickness.