I helped install an ebay 8000k kit on a friend's 02 Altima and it came out really well. Much better lighting than stock. I think it worked out well because the car had HIDs as an OEM option and the headlight housings were designed to work with them. Also, the particular kit he picked was one many people had good experiences with on various forums.

It is a bit too blue for my liking. I think I'd have to go with the 4300's because I'm a perfectionist and if there is some "ideal" to be had I want to have it.