I quite using Master Airscrew some time ago on high performance engines just because I had seen too many problems like yours.  I see two problems here: first, you are using too small a prop for those engines - you must really like to hear a high pitched whine.  Second, the GF prop is designed to give more thrust at low to mid RPM and will twist too much at high RPM.  If you want to stay with Master Airscrew then go for the higher performance props.  But on those engines you should use APC and increase the size to a 12x8.

When all else fails RTFM.