are that way to compensate for atmospheric conditions. Low runs around .95 bar with a sharper boost curve and high is 1.0 bar with a more mild curve. Most the time I run the high, but I occasionally run .95 when its really cold and the Z's tend to overboost a little. If i get caught in the rain (doesnt happen to much) I shut the bc off and run at the stock with disabled actuator setting, 6 psi. Hope that helps.