I run a 120a ESC with a reedy 7.5 in a 2wd buggy. Do I have to run the capacitor on the ESC? I would like to not have to use it. 120a is a little more than some of the other brands that I have used. Still learning the electronic side of the hobby. Thanks for any input.

Yes. It is part of the design of the ESC and they are included for a reason.

It helps filter some of the significant electrical noise from all of the transistor switching involved with the phases of the motor and the pulse width modulation for the throttle control.

Alright. Thanks man.