You can make your own pitch curves by modifying the text files. In your FS One program directory look for a folder called "RadioEquip". Inside there is a folder called "Tx". Inside there are folders for each transmitter. In that folder are the text files for the throttle and pitch curves, you can modify them to your liking.

I recommend making a copy of the transmitter in FS One and making the changes to that, and make backups of anything you change in case of mistakes.