AVO 3VOM

I'm currently considering using the Bosch HID conversion on my headlights. however, I have heard in the past that if i do this I need to program the cpu in my vehicle to produce a lower voltage for the headlights. I contacted my dealer about this and they stated that they did not discuss any "aftermarket" modifications so he would not verify if this was true or not. Basically, he was being a d_ck. Anyways, could someone verify if this information is correct, and somewhere I may be able to have it done if necessary?