for your flat serve, are you trying to add some top spin to it as well? i notice the pros, on their first serve, it bounces high as *****. when i serve my flat serves, the real fast ones always stay low and moderate pace will bounce up to about 5ft when it reaches the baseline. the balls never hit the fence on the first bounce (about 8ft away). how do these pros get their first serve to bounce so effin high?