Did you balance her laterally? Side-to-side, that is? It will make your loops and other maneuvers hold their axis better.

I hang mine from the prop-shaft and tail wheel bracket (or other suitable central point) and add cents to the high wing at an aileron servo location. When it balances I pull the servo use black electrical tape to attach the cents to its base. Occasionally I have one that needs more weight and so I use sheet lead or trimmed wheel-weights.