I'm a tad OCD. I wanted to have all my alert tones be in "Siri's" voice so I made them. Feel free to download them as they are already in the iTunes format. Just download, extract and double click to open them in iTunes. From there sync your iPhone with iTunes and set them on your iPhone. Hope you like them! Cheers!
Download -> http://d.pr/tzkb
Download -> http://d.pr/tzkb