Trap speed is not how fast you are going at the end of 1320 ft. It measures how fast you are excelerating for the last 66ft. Therefore if you have a bad launch and you are slower off the line then you are excelerating at a faster rate during the 66ft giving you a higher trap speed vs. a really fast launch which gets you up to speed quicker and you are not accelerating as rapidly towards the end of the 1/4.