If you actually have a need for additional capacitors (because you are using batteries that or only marginally suitable for the setup) just install a Castle Cap Pack and you will know you have the right components:

http://www3.towerhobbies.com/cgi-bin...&I=LXBVNB&P=ML

Castle installs the Cap Pack on the Monster2 that is used in the Traxxas XO-1.