I want to replace the light gauge strings that came with my MacKenzie & Marr guitar with a heavier gauge in order to get more power.
Replacing the factory-supplied light gauge D'Addario EXP strings with medium gauge strings adds additional tension to the neck. Thicker strings will change the playing characteristics of the instrument. The nut slots may need to be filed wider - especially on the base side - to allow the strings to sit as low as the light gauge ones. The truss rod may need adjusting to remove extra relief caused by the pull of the heavier strings. Although the guitar should suffer no ill effects you should keep a close eye on the neck and bridge. There is a slight possibility under certain humidity conditions that you will experience a lifting of the top wood behind the bridge.
The above information is really aimed at worst case scenarios. In our experience moving up to medium gauge strings on any of our guitars has no ill effect whasoever.