HID Fog Ligt vs PIAA 2500k fogs.
 

Would 2500k HID FOG light put out more light than a halogen PIAA 2500k bulb?

Anybody install HID's for the Fogs? What kit/brand did you use?

Sure it would put out more light. But also more glare AKA less usable light. The fog housings are not designed for HID bulbs and thus should not have HID bulbs in them.

HIDs will melt the Fog Light housing over time because of the heat they put off.