How do you make the standard 6 arrow quiver useful for expandable broadheads. I shoot spitfire broadheads and they are lose in the hood and when I shoot they vibrate really bad. I thought about putting a piece of foam in the hood, does anyone have any better ideas?

Wont really work very well. Kwikee does offer a style made for expandables though. Under the hood they have a clip that holds the shaft just below the heads instead of the rubber web that the heads would stick into. Not sure, but it may only hold 4 arrows instead of six.
All in all, they are still my favorite brand of quivers.

Seriously - a better solution would be to get rid of your mechanical heads and shoot a strong cut on contact head like muzzy or steelforce. Mechanicals can and do fail, and tuning your rig to shoot broadheads is a small price to pay to assure that you have the best chance of harvesting your game cleanly.