I see a water jacket in the cat, but what keeps the header tubes cool? And I'd love to see how/where the missing tube(s) goes...

It looks like with not a lot of modification, the cat-half could be mounted to a standard riser...?

I'd worry about heat without a new ECM running a closed loop system....

Looks fairly restrictive to me for an exhaust header. Especially the area just ahead of the cat core. It doesn't flow into the core the way it flows out of the core. Seems like they should have design the inlet side with smooth flowing transition instead of 90 deg joints and a small gap between the end plate and core.

This cut-away was shown on a sorta stock looking GM block 6.0L.

Well...the two O2 sensors should be easy to change if needed.

Interesting design.

It was not in their catalog the last time I checked, either.

I can't swear to it by the pic, but in my case, the entire header tube is water jacketed, from the mounting flange on out. These would be the same.

Good question.

Any answer?

Let's hope they use REALLY good rust resistant metals, I am thinking of us in salt water....OMC/Bomb triple guard grease goes on most of my bolts, but on those, only thing you can use is antisieze which can cause trouble in salt air...

What brand CAT header is that?

I took as a prototype from Custom Marine.

The O2's should not get wet?

Anti freeze kills them. I'm not sure about water.