On Friday, Zak (EcianIce), me, and a few friends stopped by the dealership to pick up a part for my car. While we were there, Zak inquired if the stock HIDs from a 330i would fit in his 2003 325i. They said it would fit, but it would cost about $7k in parts, for controls and such, not including labor.
We were floored. $7,000 to upgrade the headlights. You could get a dinan supercharger for that. =/