OEM HID question - HeadLight Assembly w/ Aftermarket Ballasts

I'm looking into the OEM HIDs for the Golf/GTI, and I was wondering if I can pick up the headlight assemblies themselves, and put in ballasts/ignitors from one of those higher wattage aftermarket kits (6000k that the GBs are goin on for). Would that be the same instead of purchasing the OEM ones at a possible higher price? I'm just asking since it's the D2S bulb that you stick into the headlight assembly and that wouldn't make a big diff b/w the OEM bulb and ballasts would they?