you wrong, it is illegal to modify your headlights in any way, in any state. Period. HID kits - modifying, retrofit - modifying, replacing halogen projector with HID projector - modifying. Your example with G35 is one of very few when car manufacturer opted for reflector housing rather than dedicated HID projector possibly to shave some cost, other examples are 03 Acura TL, Lexus IS300 and couple others. But, reflector all these cars use are DESIGNED for HID bulbs and produces somewhat descent results (you cant beat HID projector in terms of performance). Other thing to remember is what type of bulb they use. D2
R bulb again is DESIGNED for HID applications in reflector housing. If your wife's G35 has OEM headlights I can bet you money it runs D2R bulbs, go check it out.
D2R vs D2S bulb
Its easy to see that D2R (for use in reflector housing) bulb is shielded in certain areas to reduce glare and point light output in right dirrection.