igniter boxes underneath the headlight. you dont need leverllers as you are retro fitting the lights. as the car didnt leave the factory with them(xenons) you dont need the leverllrs, would recomend headligt washers. it is possable to fit adjusters to xenons.
i know a few pepole will say you need leverling you dont. as long as when the vechile is presented for test they pass the beam aim part thats fine. the reason is the car didnt leave the factory with xenons.
How do you adjust the level then, the xenon lights rely on the senors on the wishbones to adjust the lights, the sensors are an MOT requirement to ensure the ultra bright xenon lights dont blind people, if the MOT technician spot the uprgrade and looks deeper into the 'Minor' modification could fail your MOT.
Might be worth speaking to an MOT trained person before doing the upgrade to see where you stand, would be intrested in the outcome !
Just my opinion
Steve