I don't know from where you got the idea of adding the capacitor. In CD players you would normally see a capacitor hooked up between the motor terminals to suppress the noise generated by the motor. In technical terms its called a "snubber ciruit". That would not help you in increasing the RPM or torque.

I have no idea of how much torque the motor generates so, might not be able to guide you on the prop modification. If you want to experiment get a couple of props and go ahead chopping it down. But I am a bit doubtful on the outcome.

-Ismail

ok thanks
abt the idea of capacitor i saw that in toy rc/non rc cars the motors had it
when i compared two motors one with and other without a capacitor i found that the capacitor one had a better rpm and torque-the motors being the one and the same
anyways i'll try out by cutting it down...