Question pa-30 exhaust cracks

Does your aircraft have the expansion joints on the riser for cylinder #4? Some repair operations leave that out. Are there particular places that the exhaust is cracking? With previous cracks, have you been doing weld repairs or having them rebuilt?

I have a PA-30C and have had no cracks in 1,000 hours.

Hi Bob,
I asked Kristin Winter, A & P and PA-30 owner to weigh in.

The following are her comments:
"A couple of thoughts:  If a system has been repeatedly welded, it is best to get new or a complete rebuild by AWI, Acorn, or Knisley.  The metal just gets thin overtime.  Sometimes the cheapest repair is the most expense up front.  Also, the system is four parts.  Two connect together to collect from cylinders #1 & #2 and exits out one side and the other two parts connect #3 & #4 and exit out the other side.  Both pairs cross underneath the nose case.  They are a slip fit together and should be free to slide.  I paint them with C-5 anti-seize so that the two halves can slide when the cylinders expand.  If they don't slide, then you get lots of stress which can cause cracks.  The other condition that can promote cracks is when the tail pipe hangars don't really support the tailpipe, letting it bounce freely.  That is about all I can suggest.

I've owned 284TC Pa-30 for 6years and 500+ hours. A reoccurring issue has been exhaust cracking! Anybody have a fix or info on alleviating this issue? Hints, tricks, old wives tales,lol!
Thanks Bob