Don't waste your money mate.
I drive around 1000-1500 miles per week and have tried every single bulb upgrade out there.
Most bulbs only last a few months which is terrible especially when they cost upwards of £30 a pair.
Best lighting upgrade I have ever done on the Foz and the Caddy is to go HID - wins hands down everytime.
My Foz HID kit has been in for over two years and has never faltered.
The Caddy kit has been in for 18 months but has had well over that as used nearly every day (night).
Best value for money kits I found were from Lightec Autostyle.
You need the Bi-Xenon kit and 6000k is nearest to factory HID colour and you even get FREE LED sidelight bulbs - Not bad for £55 and so easy to fit - You just unplug your bulbs and replace with the kit and connect a couple of leads to your battery and another couple of leads plug into your original bulb holders:
http://www.amazon.co.uk/H4-XENON-6000K-HEADLIGHT-BALLAST/dp/B003N61WYG/ref=sr_1_2?ie=UTF8&qid=1318799128&sr=8-2Even passed two MOT's in the Foz and one MOT in the Caddy.