Question

P0430 - Can it be caused by exhuast manifold leak?

Answer 1

P0430 Catalyst below threshold Bank 2

Yes it can, if the exhaust leak affects the operation of the upstream 02 sensor,

 Here was exhaust manifold exhaust leak, not only did the owner had to deal with the noise, but it affected the operation of the 02 sensor, where is set a lean engine code condition as well as a P0420 (catalytic below thresold bank 1).