I have recently put magnaflows on my 2003 mustang GT.

I recently realized these sort of residue lines (picture attached) have formed on the inside of the exhaust pipe.

The weird thing is. the lines on the right exhaust pipe are where they are in the picture.

on the left exhaust, they are in a different location..more up the left side wall of that respective exhaust pipe...

hmmm...any idea what this is and why this would be?

thanks so much in advance,

Jennifer Holliday


Edit: Tried to post picture and couldn't :-( ....the lines look like rainbows...one of the exhausts have this symtpom directly in the middle bottom of the exhaust pipe and the other exhaust pipe has the colorful lines on the left wall of the exhaust pipe

 

It sounds like its just the result of the metal getting hot..Kinda like a gun "bluing"