I recently installed test pipes and one of the gasket on the right header broke so I went and changed it, while I was changing it I looked into the header and saw a brown looking piece of metal so I tugged on it and it was pretty firm so I let it be. My question is, what was that piece of metal, and should I try to remove it.

 

If it was close to one of the welded joints, it's most likely a bit of welding rod or slag left over. It's not really going to affect the performance of the header if you decide to just leave it IMO.

 

I thought it might be from the gasket when it went to **** but it seemed to be stuck in there pretty good, it seems to look like a piece of sheet metal if that'll help y'all diagnos it, it's the same thickness and all as what a piece of sheet metal would be. Also its stock headers on a DE

 

Trying to diagnose anything is next to impossible from behind a keyboard. If you're than concerned, take it to an exhaust or fabrication shop and let them inspect it.