I wouldn't worry about it. The actual tubing is all 304, some of the internal baffling, is apparently a diffeerent grade of stainless. If you look through a Corsa muffler, it's the most amazing design. It's like looking through a perfectly smooth tube without hundreds of perforations or ridges like all the other brands. All they have is one smooth slot at on end of the mufller about 3/8" wide, nothing else. Baffling is all encapsulated, the gases never go through it, simply amazing technology. Absolutely nothing to disturb flow. I've never seen another exhaust with this technology. All others flow into a perforated tube or some sort of baffling which disturbs flow. This is especially amazing since they are so comparably quiet, with no drone.