Making a bigger wake for wakeboarding?

okay so my parents have a 17' ski boat, and i am a wakeboarder. i recently went out with a buddy and he had a wakeobard boat, it was awesome! now i wanna know how i can make the wake bigger on my parents boat. i know you can slow down and shorten the rope, but what else can you do? is a fat sac worth the money? and btw i am trying to jump and do tricks.