I put a 2005 8.3L SRT10 motor in my 2000 dodge dakota. To keep it street legal here I need to design the exhaust to include catalytic converters. I have some flexibility on where exactly the cats go though and had some questions on exhaust design theory. The truck will be using the factory SRT10 Ram exhaust manifolds which are basically a cast iron shorty header. The pipes and cats will be 3 inch.

- Is there a specific distance from the exit on the manifold to the cat that will create the best flow through the cat? I know I don't have the space to get laminar flow or anything like that, but If I have the flexibility I might as well use it.

- I don't know for sure if I can fit a X pipe, so it will likely be a H pipe. If I can fit the H pipe in front of the cats would there be any value to it? It might cause 02 sensor issues but I could work around that if needed.

Thanks for any ideas or brainstorming!

-Jon

I am not positive on this but I think you will want to keep the cats as close to the engine as possible. I think its important they stay hot to work properly, the farther back you put them the cooler they will be.

I bet Mr. P body chimes in here. I think he used to do exhaust systems when he was at Chrysler.

I would think the same, keep them as close as you can. But i am curious also as i am in a similar deilema, big block in a '85 truck with long tube headers--i need to do at least one cat on mine.