An electric fan won't cool any better than the stock fan and stock shroud (for example, use the 120Y radiator and shroud).

However, a thermostat controlled electric fan is off when the engine's cold, and might turn off at high speed, freeing up enough HP to be significant.

The air is always drawn from outside the car, though the radiator, and ejected out through the engine compartment.

Like B310gx, I've also seen an electric fan installation cause overheating (on a highly modified engine), where putting the factory system back on fixed it. It depends on the fans, I guess. Most electric fan kits are just fine if they are correctly sized, and installed according to the manufacturer's directions.