Just got done putting my DC sports header on , and when I get to high RPM's there is this strange rattling noise, I noticed when I go the header there were a lot of packaging peanuts in it, I thought I cleaned them all out, would one of those possibly be making that strange noise? And if so would'nt they eventually burn up and that sound disappear?

 

a metal peanut probably

or loose bolt

 

I was thinking it was a loose bolt as well but I only hear it at the rear of the car and I didn't touch anything back there.