The Holley system will also increase the idle when the AC comes on. I think FAST might do that also. They have a sensor wire that connects to the AC and when it gets a voltage signal the idle speed will increase.

If you go to the Holley website and look over the features you'll be surprised at what the systems will do. They'll control the fans, control the nitrous system, control an automatic trans, allow you to use drive by wire, etc.