This deal is best when paying in GBP, as their currency conversion sucks. They often have discount codes, but 25% is less frequent.
Given that their Philips Whitevision bulbs are discounted and that the pound has dropped, this makes it a great deal. Expect to pay double this price in Australia, or more. I have found shipping to be quite fast, at about 1.5 week. I normally buy bulbs in advance, so that if one breaks, I am not forced to buy at double the price locally.
Unfortunately H11 is only sold as single.
I have used Whitevision in multiple cars. They are very white, and at the border of what is street legal. The temperature (K) on the packaging is confusing and inconsistent. I asked Philips about this once, and they said:
"The brightest bulb from this range is 4300K". There are different types of car bulbs (H1, H7, H11 for example) and they differ in temperature colour. H7s that you have bought have 3700K, while for example H11s have 4100K.
Having tried a few ones, including Narva Intense (supposed 4200K), I can say that I haven't seen whiter light from street-legal halogen bulbs.
An important thing to note is that the Whitevisions have a considerably longer rated lifespan than other "white" bulbs, and are on par with standard (non-white) bulbs. The reason whiter bulbs normally die earlier is because they are hotter.