Integrated catalytic converter.
 

I just replaced my exhaust manifold on my 03 lancer es with an aftermarket header. Do I just add another catalytic converter to the mix to replace the integrated one on my old manifold, or is there something more specific I need to do. As it is right now, I have the header to my downpipe to a new catalytic converter to my old rear converter to my muffler and tailpipe. Please help cause I feel like I'm doing something wrong.