If you are going for top dallor, stick with OEM ballast/bulb they are so much better then aftermarket stuff, what kind of bubls is in the 636? 9007?
I suggest finding a cheap headlight for your 636 and retro a pair of bi-xenon projectors, you will love the cut-off and everything. dont buy the lame aftermaket hid kit. they are a waste. oem with color mod owns!