one of the first stupid questions

[TonysX5er]

Hi fellow x5 owners, I just took delivery of my x5 a couple of months ago. I noticed that the xenon light wasn't as bright as I thought it would be, to make a long story short, I just wanna know in order to make it brighter would I have to buy a HID conversion kit or just buy a 6k ( I want pure white as my old car had it and I loved it) xenon bulb and replace with the oem stock xenon bulbs? I'm guessing its the latter but I just wanted to double check with you guys. (This is my first BMW by the way and I am loving it.) I asked my CA if it would void warrenty and he said no so I'm gonna take his word on it even though its an after market product. Anti flame suit on* ps. Thanks in advance for your help