[Angel And The Wolf]

Originally Posted by cajunfj40

Ok, more searching dug up old Stahl 360 degree headers for a small-block-chevy. https://www.jalopyjournal.com/forum/...ock-up.415461/

Thank you! That is my aim, to run each two 360 degree apart exhausts (or, each cylinder of a four cylinder engine) into one pipe, and keep each separate from the other three pipes.

Seems the headers shown are quite long, and would help low end torque, but hinder mid to high end power.
Maybe moving the exhaust ports to the middle of the engine, (See Picture) would facilitate shorter 2 into 1's.

Yes, the factory cat with walls to divide the input and the exit into four sections, as in my first idea, seems to be the most doable, and the honeycombs should keep each input in it's own quarter, and the middle chamber would allow equalization and a common O2 sensing area, though, if each path could have it's own O2 sensor, computer adjustments could be made to pairs of cylinders,(single cylinders, on a Four.) rather than to the whole engine, when only one cylinder might be out of compliance.