Without the fan and clutch there is a definite increase in power. With the electric fan(s) on there is an increased electrical load but no more than the alternator has normally. The only question is how much is the power gain. Less than 5 HP is hard to feel when driving. If you could tell the difference it would immediately become "normal". I remember a big debate in circle track racing about the "Ram Clutch". It went into a mechanical lock up once underway - no clurch slippage. One of the doubters said, "yeah, how much is that good for - a hundreth of a second? The answer was, "Hey, ten of those is a tenth!"
Any body got nine more?