horsepower to weight is important.....
but at extreme speeds what is more important is aerodynamics(i think that is how its spelled). Bikes just cannot compare to cars in that regard. you can see it when he is racing the viper, the faster they go the Viper just starts to leave him.
TORQUE to weight = acceleration
Power to CdA = top speed
Personally, though, I've never understood these midnight 'races' on the highway going from 60 to whatever. Find a good technical race track and let's compare lap times.