If it is a conventional aircraft: monoplane with an aft horizontal stabilizer that is not a lifting stab as in some vintage types Then the 25 to 30% figure is indeed the way to go for any sport airplane. Yes some extreme aerobatic types as well as some pylon craft will exceed this somewhat but not much. The only other exception to this is flying wings which need a more forward cg around 15% or thereabouts as well as tandem wing/canard craft.
Going to anything beyond around 33 is looking for trouble.

John