CFTS talked about Ben Johnson breathing only twice/three times in one of his races. Do you guys always use the vasalva maneuver during sprints, even in GPP and practices?
Just breath naturally and you will get the effect you want. Charlie has spoken on this numerous times - there is no secret.
With my group - I apply valsalva - however in the acceleration phase i tell them to exhale when they feel like it and that should take them anywhere to around 30m