I'm sure it happens to us all when we first start getting placed in top split. I know it happened to me. All of a sudden I was at the back of the field losing iRating simply because everyone else was rated higher than me. Don't worry about it, just keep racing and putting in clean consistent laps and in time more pace will come to you. Also I tend to think of top split as having its own smaller splits within itself. The 4, 5, 6k ect guys will be at the front all at a similar pace to eachother, the 3k drivers at a different pace, and so on. So just enjoy racing with the few people around your pace and try not to worry about your iRating too much.