scratching noise

[cencal559]

hey guys i need a little help. i have a 96 ls teg and when i am in neutral and rev it high as it goes back to idle it will make a scratching noise?

 

[OlegWasHere]

where is the noise coming from?

i remember a while ago whenever i reved in the higher it kind of sounded like scratching and it was my air filter(the bottom metal part was loose)