Here is some video of an alternative way to try a tantrum, it may help you get your timing down. I did them this way for a while, because I was getting the rotation, but no pop because my timing was off. I watched the wake over my front shoulder all the way in, and turned my head after I was popping up. now I can hit them the regular way with huge pop.
Take a very aggressive approach, one that is much faster than a typical wake to wake because you will lose speed on the trip. let go with the back hand as you are starting to stand at the wake(remember to keep the line tight). When your legs are extended, rock your head back. this should happen at the very peak of the wake the instant after you pop, but before leaving the water. too much before hand, you will rotate low and fast. to late, you will pop, and not make a full rotation. http://www.wakepics.com/view_single.php?medid=8950