Originally Posted by aajami
It is made of a different material. Stock exhaust is primarily stainless steel. M Performance exhaust is Inconel and titanium.
Just curious, have we confirmed that? As mentioned before, there are lots of high carbon steels that fit the description of the material. Judging by the heat marks left by the welds, it looks like MiG welds, which are not appropriate for Ti or Iconel. (you need to TiG Titanium)