I'd put thin layer of rubber between your clamp
and the psru. Same concept at harmonic damper on engines. In theory it would

reduce stress concentration at your muffler outlet. FWIW
-al wick
-------------------
That makes some sense to me.  Although I'm not sure what sort of material
one would use since the temps on the re-drive can get over 200F.  And there
is the possibility of making things worse - things have been fine for 100
hours and no signs of any "movement" at the clamps.  Adding some flexibility
would change (lower) resonance frequency and . . .

My thinking is the critical weld is not at the end of the resonator; but the
ones at the header/tangential muffler joints; but I could be wrong.

Al Gietzen