Negative expo actually makes you move the steering wheel more on the radio. Spektrum is backwards from all other radio manufacturers, postive expo makes the steering less sensitive. I run anywhere from 10-30% negative on my m12. Smooths the car out and keeps the front end from "slamming" down on the springs which can cause lots of other handling issues. Quite honestly it's hard to tell you what to run as it's all driver. Use your duel rate to set your turning circle then use expo to get the "feel" you want. My turning circle is usually around 3'. I rarely change it, I use the expo the most to get a comfortable feeling in the steering wheel.