I stumbled across the original manual for the G.50 in my downloads folder today. I got it from FG28_Kodiak originally. It's in Italian but the information is easy to understand especially the numbers on page 90 which you should take a really good look at. For example, practical service ceiling: 10,700 meters(!) not the 4000 meters "roof" you hit in CloD. Also, 470 km/h (TAS I presume) at 5000 meters. I tried to PM you but your inbox is always full. Please try to find the time to look through it so the G.50 will get at least somewhat better FM than it has now. Here's the link to the PDF file:
http://uploading.com/files/8d8eab2m/...5933-6247.pdf/