3 world records for you:
1. 400m: Michael Johnson, 1999, 43.18 seconds (10.80 seconds/100m)
2. 100m: Usain Bolt, 2009, 9.58 seconds (9.58 seconds/ 100m)
3. 4 x 100m relay: Jamaica, 2008, 37.10 seconds (9.28 seconds/100m)
If you want to be fast, focus on the runner, buy the best shoes; and most of all focus on the goal.
But, if you want to be really fast, do all of that, and then, focus on the baton.