I had the same problem with my Sig Cap 231 Breitling. It would snap when I applied full rudder on high rates when I was going full throttle. High speed snap.

I know this sounds crazy, but try adding some tail weight. It worked for me.

Here is a way to tell if your plane is truly balanced:

Full throttle flat and level
Pull too a 45 degree upline
Roll inverted

Don't touch the sticks once you are inverted. Do not add down elevator.

If you are truly balanced, the plane should continue inverted on a 45 degree upline. If you are too nose heavy, the plane will start coming down. If your too tail heavy, the nose will rise and the tail will drop.

The guys at Aeroworks came too one of our club meetings and gave us a seminar on how to trim planes. The above mentioned method was one of their procedures for balancing a plane.

The reason you need tail weight, (I think) is because one wing is stalling first at high speed and causing the snap.

After adding tail weight, both wings will stall at the same time. You should be able to come in full speed, flat and level and hog back on the elevator too bring the plane too a full stop and in a hovering attitude.

I did this too my Cap 231 and now it doesn't snap.

Be careful and add tail weight slowly. After the correct balance is achieved, the elevator on these aerobatic planes becomes "SUPER SENSITIVE".

After you have it properly balanced, only then should you add the Exponential. Adding the Expo. on high rates will help you with landings.

I know that the advise I have given goes against all conventional wisdom, but I'm telling you; it works.

gimme a minute too get my flame suit on................... okay, flame away.