my car is kinda jacked up to put HID's in.. my head lights are huge and have bolted on covers to access bulbs for changing.. but you must remove the entire light structure and there is a1 huge block plug for all the wires.. confusing i know. i was going to drill holes for my wires and mount my ballast outside and what not.. but i was talking to a guy on youtube and he said he mounted his ballets inside the headlight structure ... there is room.. but my thoughts were how hot do the ballast get? i have never touched them to find out.. i have the small ones,. made by Xentec