[jhandy]

ok, here is what i have seen with my car. It may be different with someone elses...

The battery does not get a good charge with the 4inch pulley on short rides and at idle. I have accidently run my battery down by playing my radio while in the garage, and the car can drive fine, start fine, but if the battery is already crap, then the alt does not seem to recharge it quickly.
Now if I am not stupid and keep my battery to start the car and nothing else, it does just great.
There is no bad side when driving with all electrics on. I have measured the output while driving and at 1000 RPM and greater the charge is 14 volts.

So there is not a downside to a 4 inch pulley that i can see. Just dont run your battery down with the car off.

So... you meant an underdrive and a larger steering pump? why would you do that? I have not noticed any downside to the steering.