ORIGINAL: jimmyjames213

EXP Exponential Settings (from http://manuals.hobbico.com/fut/4ex-manual.pdf )
Negative exponential (-) decreases initial servo movement. Positive exponential (+) increases initial servo movement. The
exponential “curve” may be set anywhere between -100% and +100%.
To set the exponentials:
1. Enter the programming mode. Access the “EXP“ screen with the MODE key.
2. Select the channel (1-aileron, 2-elevator, 4-rudder) you wish to set by pressing the SELECT
key. The active channel number will be displayed on the screen.
3. Enter the amount of exponential with the DATA INPUT lever.
4. Repeat for the settings on the other channel.
Note: Before programming the exponentials, perform trim memory operation and then set the corresponding trims to center.

thats for your tx. what negitive expo (what you want) does it make the initial stick movements not as sentisive as the corners (or farther out depending on the setting
for example your rudder moves 3 inches, what -100 expo will do is make the full tx input give the full 3 inches of throw, yet 90% tx inputs will give you 1.5 inches of throw
i use between -20 to -40% expo depending on the plane. this just makes it easier to correct for little errors yet when the wind gusts still give me full control of my plane (think dual rates without flipping a switch)