Just to confirm, it's doing the rev limit of 3500 in park or neutral, correct?
If so, that might be normal.
AKA a 'soft limiter' is fairly common these days (even back to 2008).
We don't have my wife's cx9 anymore, so maybe someone else has one to try a neutral/park rev test.
I agree with sm1ke, that's not a catalytic converter, it's flex connection.
It looks like it was replaced based on the welds, but the factory exhaust has one in that location.
The catalytic converters are located right on the exhaust manifold.
Picture below from Rockauto seems to match (but with better welds
)
EDIT: I think the downstream cat is in that pipe, but to the left of the flex pipe.
2007-2015 Mazda CX-9 part # CY01-40-550E - Intermediate Pipe
www.tascaparts.com