these same things about beam pattern are one of the many reasons hids are not legal unless equipped from the factory.
right from the nhtsa actual letters to people and companies...
http://isearch.nhtsa.gov/files/Shih.3.html
Because replaceable light sources are, by regulation, designed to be non-interchangeable, it would not be possible for an HID headlamp conversion set to meet the standard’s photometry requirements for an original equipment headlamp system using a halogen light source, so the replacement lamps could not be sold for this purpose. Furthermore, a headlamp dealer or motor vehicle repair business could not remove the original halogen headlamps and install HID replacement headlamps without violating 49 U.S.C. 30122. That section prohibits manufacturers, distributors, dealers, and motor vehicle repair businesses from making inoperative equipment installed in accordance with a Federal motor vehicle safety standard. We cannot comment on the specific replacement lighting products that you mentioned because we do not have sufficient information on them.
http://isearch.nhtsa.gov/files/deetz.ztv.html
The kit that you furnished us appears to be designed to replace an H1 replaceable light source, and consists of two parts marketed under the name "Thunder Beam." The first part is labeled "HID Bulb Set" and contains two replaceable light sources, identified on the packaging as "WB-H1." The second part is labeled "HID Driver Unit TD-5000," and contains a ballast, an ignitor, a relay, and adapters to convert the motor vehicle’s wiring harness to be compatible with the HID conversion kit.
Based on a review of the H1 light source specification filed in the Part 564 docket (#3397), it is apparent that the Thunder Beam HID Conversion kit is a significant redesign of the H1 light source. At the most basic level, an H1 light source incorporates an incandescent filament in which light is produced by a metallic wire coil heated to incandescence by an electrical current, whereas the HID conversion kit’s light source incorporates a discharge arc to produce the light and requires a ballast for operation. Thus, in order to comply with paragraph S7.7 of FMVSS No. 108, the Thunder Beam light source must comply with, inter alia, the dimensional specifications for the metallic wire coil filament size and location, the electrical connector size and location, and the ballast would need to be a design currently on file for use with an H1 light source. Complying with the dimensional aspects of the H1 light source appears to be an impossibility considering that the wire coil filament and the electrical connector are not a part of your design. Furthermore, there are no ballast designs on file for use with an H1 light source. Thus, your company’s HID conversion kit is not a design that conforms to the Standard and could not be certified as complying with FMVSS No. 108, nor imported into or sold in the United States.
http://isearch.nhtsa.gov/files/kim.ztv.html
HID conversion kits are illegal if any item in the kit does not comply with Federal requirements for vehicle lighting equipment. Please read the letter carefully and apply our analysis to the components of the kits you are selling. If one or more of these components does not comply with FMVSS No. 108, then you should cease the sale and distribution of this equipment. Your failure to do so could make your company liable for civil penalties for violations of 49 U.S.C. 30112(a). If your company manufactured or imported noncompliant HID conversion kits for resale, your company is required to notify this agency, dealers, purchasers, and owners of the kits and to remedy the noncompliance in accordance with 49 U.S.C. 30118-30120 and 49 CFR Parts 573 and 577. I should advise you that we know of no HID conversion kit that can be certified by its manufacturer as complying with FMVSS No. 108.
