Hi Gents,
Thanks for feedback. My question was based on further questions i wanted to ask, hence you guys answered some of them already.
I would assume, if the cats are situated on the manifold you have two options.
1) Remove the manifold, Punch out the internals of the cats and re-install the original manifold as is.
2) Manufacture and entire new manifold/branch.
I would think cutting up the original manifold wont be a good idea.