Flex time transient markers

When I first turn on flex time it sets the transient markers not quite at the zero crossing. So when quantizing it often splits the transient at a bad spot creating a pop. Is there a way to automatically tell logic to set the transient markers back to the nearest zero point before the transient. Also it seems like when I use the plus and minus buttons to set the transient threshold there is a point where it finds too many transients or not enough. I need better fine tuning for the threshold is that possible?