I have broken two separate exhausts on my 360.  The first was after about
120 hours, while the plane was still turbocharged.  The turbo exhaust pipe
broke off where there was a sharp bend.  Probably too sharp, and probably
not as related to vibration as it was to heat.

The second break occurred about 2 months ago with my non-turbo installation.
I have 4 separate pipes coming from each cylinder - they are not tied
together.  The #1 & #3 cylinders kept trying to break the hangar bracket
(near the firewall, flexible material coming down from the engine mount).
After breaking the hangar, the exhaust pipe for the #3 cylinder broke off at
the exhaust flange.  It was dangling from the EGT prope wire when I did my
QUICK turnaround to land.  I had been airborne about 5 minutes when it
happened.  That gets your attention.

I now have a revised mount, but there is a still a flexible support coming
from the engine mount to the pipe (each pipe is about 36" long - too long
not to have some support).

Matt