Get a DD 1008 http://www.ddaudio.com these are the most impressive 8's I have ever heard //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
yeah 400 hz is almost lower midrange, without a doubt midbass territory. Peerless XL 8's are a good driver if you can find them. Nextels are good too. I think someone linked to the ever popular daytons already.
Regardless if you just looking for a raw driver, you can get a much better performance/price driver than that infinity. Check http://www.diymobileaudio.com if you already haven't.