Mind you, a PA31, loaded to the gills needs every bit of HP it can get. Any RV with more than 160HP is massively overpowered. My -9A will get around 1800FPM with a FP prop and makes 145KTAS spinning at 2400RPM at 8500. Unless I was building a -10, I'd never waste the money (or the weight) on a CS prop.