twisted minis
+1y
Yes and no. Thin steel will get hot and cool down faster, but with constant heat going through it, it will always get hot. Thicker steel requires more heat to become hot to the touch. However, the most common muffler thickness is 18 gauge, which is about .045" thick. 16 gauge is .060" thick. Not much of a difference. Most mufflers get hot regardless though. Have you ever touched one while the truck is running? They are always hot, but the catalytic converter will get up to 3 times as hot. Cooling fins would make it taller, which would somewhat defeat the purpose. Its meant to provide ample room between the exhaust and the floor, and the thicker gauge material means it can come in contact with the ground and not do much damage.
Also, flowmaster makes 16 gauge mufflers, and now even makes 14 gauge mufflers intended for rock crawlers.