I have the same problem!
The settings you refer using MAC codebase are into the file NV_DATA.h
/* Energy detect threshold for determining a clear or busy channel during an Energy Detect operation from the MACA */
#define gCcaThreshold_c 0x39
#define gDualPortRFOperation_c TRUE
#define gPowerLevelLock_c FALSE
#define gDefaultPowerLevel_c gAspPowerLevel_3dBm //hex: 0x11
#define gEnableComplementaryPAOutput_c FALSE
#if gTarget_UserDefined
/* User defined tuning values */
#define gXtalCtuneValUserDefined_c 0x04
#define gXtalFTuneValUserDefined_c 0x0E
#endif
The MAC stack drives internally this signals. But with this settings I can't reach the best tx power.