I tried silvania silverstar in my accord and thought it was $40 well spent, since visibility increased noticebly. The bulbs are blue, but the light is just white, not really blue. Only problem - they burned out every 5-6 month, which shouldn't be a problem since you dont drive your car often. I later switched to silverstar ultras - they worked great about a year, but I stoped driving my accord because of blown tranny (who said hondas are bulletproof?
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I would not advice installing more powerfull bulbs, since I heard they melt our plastic headlights and speed up headlight's yellowing.
On boxster - I went with a 6000k hid retrofit (not litronic), since I do alot of night driving and wanted the best visibility I could get. That really was best $100 and 30 minutes spent on my car so far.
Alex