I also have a Sig SE. Many people are enlarging the tail surfaces, mainly the rudder, and using new hardware for control linkages. I know of a few, me included, who are double-beveling their surfaces to allow close to 80 degrees of throw. There are many other mods that people have done.

If you do a search on RCU, you will find tons of information on Sig SE's. You'll find that this is a very popular airplane, and many people will have GREAT advice on how to build it better.

Cheers,

Patrick