Nice discussion guys I understand now too!

I pulled out the Bosch Handbook checked out alternators - indeed the more current required, the greater the magnetic field, the greater the torque required to turn the alternator shaft.

Thus turn on headlights - more torque required to turn alt - rpm may drop.

Best thing is I was right and my mate was wrong....I better make a phone call.

Thanks again - this is what forums are all about.

As for electric water pumps,if it's a daily...don't go there as you may end up having cooling problems in traffic snarls,constant ideling etc.as the coolant is getting wizzed through the radiator that fast that the coolant gets no chance in the core to be cooled by the fan pushing air past.

Now for competition where your running between 5000-9000 rpm constantly they work a treat and also reduce cavitation which you get around 7000 rpm with a standard pump.
Even with an electric pump for racing you still require some sort of flow resistor(modified thermostat) to keep water in the cores a bit longer to be effecient.
And yes,you will pick up a couple of free HP with an electric pump.

Hmmm - good to keep in mind, maybe one day when I get desperate for horsepower I can have this one up my sleeve, the alternator trick is interesting as well.