I have an idea for a character, and I was thinking about giving super speed as their only power, with no other abilities or powers or anything. How fast at max should they be be able to move? Of course having super speed means that they have everything else that comes with it, super fast metabolism, reflexes, senses, etc. Like would anything under the speed of sound (767 mph) be reasonable or would the number need to be relatively low to super speedsters standards?