hey... a long time ago, I used to sell lightbulbs (non automotive, sadly) ...but, generally speaking, it's the fixture (the projector, reflector, lense, wiring assembly + OEM bulb) that's dot approved.
so, yer pretty much all set if you stick with h1 bulbs... in your m3;
the ellipsoid fixtures in the E30 are E1 approved (european) but not DOT, even with the same h1 bulbs
anyway... you want osram silverstar H1s...