Hi,
very important while turning with a 109 is to reduce power.
With WEP the 109´s dont decelerate enough to turn well, specialy while a downward fight.
Only use WEP as long as you have a real advantage to keep it, or while flying strait(climbing). But if you evade, dissable it and also try to reduce power, then the 109G will turn very well, but dont overstress this.
Greetings,
Knegel