RE: Picco 45 DF
Try an APC carbon prop # LP 74825C 7.4X8.25.
You don't need to worry about the prop going away and you'll get the engine into it's designed operating range.
Re-tune the pipe hopefully in the 24,000 to 25,000 range on the ground. A #1150 pipe, #1250 Muffled or the #1050 Quiet pipe may work better on a DF engine (one size larger than a sport engine would use).
Even the 8.8X9.75 pylon prop can let-go when a strong 45-46 DF engine unloads as seen in the pictures.