60Kg and 330W for 20 minutes. Let's call it 310W FTP. Looks Cat 1 to me. Assuming you are a Cat 4 or 5, you should attack hills and should win/place in every race. I'm jealous. Just sounds like you need to learn how to ride the bike because descending at 18 mph when others are coming down at 35mph is a problem. Is your bike not stable at 30+?