Consider this very strongly. Some of the good manufacturers have even stopped sending out 55w ballasts. TRS still does it but usually does not recommend it unless the application is for off road use.
Remember there is a term known as HID blinding used for the driver of the car. The HID light is so bright it causes you to not being able to adjust on anything apart from where the light is like on the far side of the road etc. So consider everything and read about stiff like this if you want to come to an informed decision.