I did win, it was super hard to beat the Tournament but I ended in first place.

then you didn't actually win it, you need to get 1st place. And there are tons of part, you only have a chance of unlocking each

Well, I won the tournament once, but Im not sure if I got a part, I just got tons of Bytes.

That was slightly over a year ago, so I'm not quite sure. If it's a rare or a boss part, chances are you can get it as a tournament reward

Where do you get this head?