neurokinetik - there is a user at XModRC thats using a similar FET setup on his Civic. He's using a voltage regulator to keep the board regulated to 5v while allowing as much power(well, to a point - 25v) as possible to the motor.
You can see some diagrams and info on the setup he's using
here.
In your setup, are you still using a zener setup to regulate the board power or have you applied some sort of on/off Vreg to regulate your board as well?
I may attempt this mod, just trying to figure out the most optimal setup.