why ex header than lx/dx header setup

[wetcmonkey]

i google and i search and the only reliable info i find is difference is the way it is setup, but not in a way of performance is it better at all or does it just look cleaner? i may not be searching anough but i am only limited to my phone right now.

 

[cgpEJ6]

the D16Y7 has the catalytic converter built in to the exhaust manifold. The D16Y8 does not. Aftermarket companies don't make headers with the catalytic converter built in so when people want to run a header, they switch to the Y8 setup

 

[wetcmonkey]

the D16Y7 has the catalytic converter built in to the exhaust manifold. The D16Y8 does not. Aftermarket companies don't make headers with the catalytic converter built in so when people want to run a header, they switch to the Y8 setup

what does that mean in numbers anything at all? better flow, i know what makes them different in setup, why is ex better?