I installed the same HID's I will be installing in the Yukon into my V-Rod. I hope to have some better night pictures tomorrow. These are 8000k and both ballasts were mounted inside the air box. There just wasn't any other area with enough space for the ballasts. The air filter sits in the channel you see at the bottom of the box. Many guys cut these boxes with extra inlets for better performance so no harm was done trimming a hole for the wires.
I love the color and intensity of the light. They should look bad ass on the front of my Yukon with the Low, Highs, and Fog HID's on.
The Vrod has both High and Low HID's installed with the ballasted stacked one on top of the other with a 1/4" space in between for cooling.
Pics
Ballasts
Low
High