NO! You do not need to run the power capacitor on either LRP Quantum (1 or 2). They work fine without them. The manual even states this. The function of the power cap is pretty simple. When you gun the throttle, the motor pulls and extremely large amount of current from the battery. In high performance esc's like the Quantum, the motor can pull enough juice away from the receiver and the servo causing serious radio interference. The power cap is there to store some energy from the battery. With the power cap in place, now when you gun the throttle or need the power, instead of robbing your receiver and servo of power, the motor will receive any extra needed power from the cap. All the cap does is store power from the battery for the motor when it needs it.
With the cap, your car will have more punch but it will cost you some runtime. For the power cap I would only go with the LRP worlds kit. Not all caps are created equall and different ESC require different caps (not all caps are made to the same spec's - some store power faster than others...the requirement of which cap will work on your car depends on the speed that the mosfet's in your ESC open and close). The Novak cap will work on the LRP but if you want maximum power and function, stick with the LRP cap...buy the World's Kit...but you might not need it. Hope this helps.