Here are some things to consider.
Make sure the ballasts are mounted securely and you are ready to buy replacement bulbs relatively regularly. I used them on my EP3 for around 4 years and had to replace bulbs around 8 to 10 times. They say that they will last 50000 hours or something but that never happens and the gas chamber always ends up splitting due to heat build up. I always had to keep spare bulbs in the car just incase one went while it was dark.
Buy the 55W ones as the 35W ones are just not bright enough unless you do city driving. 5000K is white 6000K is blue/white. I personally think that 6000K looks better and more modern.
Please also be aware that you can have heat staining on the inside of your headlights from them after a few years. This can dull the reflective ability of the headlights over time.
I now run with Philips brilliant white bulbs that are around 5000K. They sell for around 35 quid but look great and will last years.