It does make some sense. Think about it.

What is the primary purpose of a header or headers? It's primary purpose is not necessarily to create better flow though that is part of it. THAT IS the purpose of a high-flow cat. and exhaust, to free up the flow.

The purpose of a header, via it's wall thickness and the bends in the metal, etc., is to change or hopefully make better the sonic pulses sent back into the engine. The idea behind header science to to optimize these sonic pulses for the application it's going to be used for. The sonic pulses help to make things more efficient, like burning fuel more completely, etc. Of course, it's technical and I don't understand it all.

So, that's why it's cool if you do a header first. A more complete/better solution is to change the intake back through the output; right? But a header is OK for the first step. And evidently, I must not be the only one that thinks like this.