If you're flying a showtime and pulling full elevator quickly to "pop" the elevator, I'd bet a large sum of $ you're inducing the snap. That plane is designed for 3D, which means large control surfaces.

Get your hands on a trim chart and follow that step by step. That will help you identify any trim problems. Others have told you how to see any misalignment between the elevator halves, and its worth looking at, but the snap roll is a tendency of any aerobatic plane, and learning how to manage it can be fun.

As far as initiating the snap roll, I normally do it at about 1/2 throttle, then simultaneously input full elevator (up for positive, down for negative) and kick the rudder (left or right depending on the planes preference, and usually left rudder for positive, right rudder for negative). I release the controls about 3/4 of the way through, but again this is plane dependent. If you start with sufficient airspeed, the plane will be able to continue flying on almost the same line it entered the snap, but the higher your airspeed, the more violent the snap. And none of my planes need ailerons to snap.