youtube to mp3

This website is designed to convert youtube to mp3 this is done on the site and completely free. I guess the question I am asking is how can you increase the quality of the MP3? If the video is lower grade how do you increase the quality of the Mp3 during the conversion process. All that being said this site makeitmp3.com is the best I could find. They don't make you fill out any annoying surveys and they do not limit the amount of conversions you can do.