I recently installed a magnaflow kit on my car about 2 weeks ago. the kit was a used kit. As i got everything put on i notice the tips were discolored. When i say that they look like they have a brownish flim on them. I have tried NEVER DULL to bring it back, I have used hot water and dawn soap, used wd40 to get other crude off of it. and the discolor is still there. they only thing i can see is to used 0000 steel wool on the tips but they are polished and i do not have any sort of metal buffer for them.