All depends on the condition of the AC system. AC is going to yield you the biggest gains. Reason why I asked about your goals on the UD pullies is when rpm are lower is when you are going to notice the potential for lower power and less cooling. Say you are doing a good amoutn of city driving, AC will be on, fan speed will be maxed, cooling fans on etc etc. Most of us in cooler states don't think the same way, we have a lot fewer days of extreme hot.
I have a buddy that lives in Phoenix and has an electric water pump that he runs in the winter, for summer he swaps back to a stock unit. This is because while the EWP flows plenty for most of us, in AZ he needs the added speed on the highway that the stock pump provides. Now he is modded heavily, but still our motors do generate a good amount of heat which is more problematic in the hot climate states.
AC robs enough power to typically feel it kick on and the IAC will idle the engine up to compensate. No other accessory is noticed like the AC compressor.
