Pads are the real key here. If you are running stock rotors and stock pads, I don't think your brake ducts are going to cool enough. If you are looking for a real impovement then you'll need to get some agressive pads. Agressive pads can keep their friction even at 1300+ degrees. Stock pads lose their friction around 700 degrees. Of course bigger rotors can absorb more heat and cool faster so that may be another avenue for you to look into.
