I need a youtube to mp3 website

Hey guys, does anyone know of a free online service that converts YouTube links to MP3 files at 320kbps?

And I mean actual 320kbps, not just a number, because most sites claim to have a 320kbps option

However, in reality, when viewed through a spectrogram, the frequencies are cut off at 16 kHz, whereas they should stop at 20 kHz If the file was an actually 320kbps