Stupid Question from a noobie

Hello, I have recently took on a project BMW under my wing. I have a 01 E46 325Ci ZPP that needed some TLC, after new suspension, entirely new brake system and entirely new steering rack I am now getting Cat efficiency codes on bank 1&2. I am installing performance headers on the motor after rebuild anyways but noticed that the OEM cats and direct fit cats are actually part of the exhaust manifolds themselves. So my question is can I run a high flow cat or universal cat welded directly after my headers or will they even fit or have enough room to tuck them into the body of the car without bottoming out on bumps.



I apologize in advance for the term "performance headers" let's just say a polished stainless steel exhaust manifold lol.

Stupid Question from a noobie