Try either increasing or decreasing the time, meaning in the former case that it has more time to home in, or in the latter case less time to move over.
What is basicly happening is that a torpedo gets the trajectory + speed of the parent torpedo, but with a boost in a direction, away from the original trajectory (otherwise they would all follow the same path, now wouldn't they? Nevermind the cool effect ;)).
This tech really likes it's guidance for projectiles. ;)