I'm not sure if anyone mentioned that there is a price to filling up a capacitor. That part does not happen for free. A bigger cap will require more draw from the battery and more caps will need even more draw to fill up the cap.
Not a big deal when you are at the start of the race with a newly charged battery but more of an issue towards the end depending on the type of course you are racing on.
Remember, everytime it discharges, it must be filled up again. The bigger the cap the more that it will need.
So, there is a give and take effect and a point of diminishing returns.
That is not to say they do not work, just that there are limits
POOKYT:
Small one for Stock: There are fewer spikes because the motors draw less and 3300s can handle the load.
Large one for 19t and mod: Larger current draw more spikes in power.
More important for technical tracks where you are on/off throttle more often than flowing long tracks where you can go the whole race without going off throttle.