Actually it depends on the load and the battery condition. The point is how to sustain the supply voltage level for the ESC for the instant voltage drop while at full load. Although I didn't have a low turn motor and haven't gone to measure how much voltage drop (battery cannot sustain) during the turbo turned ON, I believe a several thousands uF has to be enough for our RC car, e.g. 1000uF x4, 2200uF x4 (my motor is 10.5T with turbo).
We can use a high capacitance capacitor there for sure that will not have problems on the electronics, except for the size we always consider for our tiny RC car space. If I have four 2200uF with a reasonable size and low ESR, I will have no more considerations.