Symmetrical exhaust system on subi swap ?

[Crankey]

Hi all...so just daydreaming.
I was thinking of a system where the manifolds go out and towards the front of the van, elbow U turn up and towards the rear. Then go through mirrored elbow cats and down to the muffler can which has an inlet and tail pipe on both ends.
Magnaflow has parts that can do this.
But I wonder what about the sensor port before the cats ? Do you weld in 2 bungs for them and wire them together ? How would that get resolved ?

Anyone with enough experience to predict how well this could work ? Pretty sure I've seen dual cats on Porsches.

Also concerning exhaust systems, what determines how loud it is/will be ?

Thanks for any thoughts