It turns out the support brackets for my exhaust pipes were a little too rigid. I thought the hangers would provide enough shock absorbency, but I guess not because one of the pipes cracked and completely separated from the stack about three inches from the engine. I was fortunate though because it happened in the final five minutes of an hour long flight so I was close to the airport. The cabin of a Tailwind is pretty loud in flight, but the sudden sound of machine gun fire really wakes you up!
The plan now is to install some ball-joints into the system similar to snowmobile exhaust. This will allow me to run rigid short stacks and then the remaining length of pipe will have a lot of flex capability.