General drum No.13 is made of stainless steel. Generally speaking, the head and middle part of the exhaust pipe are made of stainless steel, and there are also all titanium alloy products, mainly for light weight, and the total mass difference will be 3kg, which is very valuable for racing cars whose speed is money. Ordinary products are all stainless steel, which will be oxidized to yellow above 200℃ and gray blue between 700-800℃. In the same situation, if the titanium alloy material is oxidized, the color will be brighter. There are many kinds of materials with short tail of exhaust pipe. Generally, the original factory uses aluminum alloy or stainless steel. However, in recent years, new cars have short tail of titanium alloy directly. In addition to titanium alloy and aluminum alloy, there are more stainless steel and carbon fiber. Lightweight carbon fiber, but carbon fiber is also very fragile. I wonder if you have heard of resonance broken carbon fiber. Many exhaust systems, especially two-cylinder vehicles, will break if the vibration frequency resonates with the natural frequency after a certain speed is maintained for a period of time.