Theory: The current draw is at the absolute maximum when accelerating hard from a dead stop, which will cause the battery voltage to drop. If the capacitor bank is large enough it could help to reduce the voltage drop. It'll only be of any use during the initial moments of acceleration as it'll discharge pretty quickly.
Practice: I don't have any experience with no-prep drag racing, but in 4WD TC it's pretty easy for a 4.5T motor to break traction when accelerating. I'd be surprised if a capacitor bank would be of any practical use as I'd have thought that traction would be the limiting factor during initial acceleration, not battery voltage.