Catalyst problems 1998 Z3
 

I replaced the exhaust with a new catalytic converter and new O2 sensors. Drove for several months and the check engine light came on and there is a rattling noise in the catalytic converter. Took the exhaust off and it sounds like something is loose inside the converter. This is the same problem I had before replacing the original exhaust. Any thoughts on why this is happening?

The exhaust has a counter weight clamped to the pipe between the support from the transmission and the catalyst. Does this have to be adjusted or possitioned in a specific location?