I can't get as high as others!!!!!

I bought a tower and some extra weight for my boat but I still won't go high enough!

I just approach the wake as fast as possible and try to keep my legs strait. I do get some good air, but I just can't get higher.

When I look at other wakeboarders from the side it looks like they are slowing down when they approach the wake. And then they get pulled straight up into the sky! I guess they do that to get some tention in the line. I have tried to brake like I do when I'm snowboarding to get tention. But it just doesn't seem to work.

I also think my line is not one of the best quality. It stretches a bit. I'm going to buy a new line tomorrow. But will that help or am I doing something wrong? How do I get more tention on the line?