ObjectTemplate.SetSpeedDev

MDT description

How much deviance to add for moving (walking/running):

x - maximum deviation to add
y - how much to add for each move forward/backwards
z - how much to add for each strafing move (moving sideways)
w - how much to reduce per server-frame (30 fps)

All x-values (maximum deviation) of SetFireDev, SetMiscDev, SetSpeedDev, and SetTurnDev are added together.

Source and more details