Common advice when moving a centre fin is: move it forward for a looser feel and better turning ability or move it back for more stability and drive. What is meant by the term "drive"? Is it speed down the line or more speed out of your bottom turn or something else?
Drive is maintaining speed, line and control on a wave and through your turns... basically the more 'drivey' a fin set up is the less chance of loosing control...
