Carenado has just released the PA31 Navajo HD Series for FSX and P3D, here are the details..
Features
Carenado GNS530 with Reality XP integration option.
Original autopilot installed.
HD quality textures (4096 x 4096).
Volumetric side view prop effect
Dynamic propeller shines effect.
32 bit real Lycoming TIO-540-A 3D sounds.
Customizable panel for controlling windows transparency, instrument reflections and static elements such as wheel chocks and sights props.
Real behavior compared to the real airplane. Real weight and balance.
Tested by real pilots.
Realistic night lights effects on pan