I personally recommend theese King Air Addons:

Flight Dynamics:
http://www.fsd-international.com/flight_dynamics/FSD_BE350_V2.0.zip <---- By Steve Small

Sound:
http://www.fsd-international.com/flight_dynamics/FSD_BE350_V2.0.zip <----- By Leon Medado

http://205.252.89.41/library/sendfile.php?DownloadID=13123 <----- Upgrade of Leon Medados sounds


Read how to install in readme.txt following the files....

Freddy Wilhelmsen
Feb.2002