changing bitrate on RFM69?

[labusr]

Hi,
I heard that changing the bitrate could increase your communication distance. Is that true?

If so, I'd like to play with it.  I only saw a previous thread talk about changing the bitrate by modifying these lines in the .cpp file:

#define  RF_BITRATEMSB_CUSTOM  0x2e
#define  RF_BITRATELSB_CUSTOM  0x66

Is that how we're suppose to change the bitrate?  I read the default is 4800kbps, but how does the different kbps translate to those MSB and LSB values?