No chance, or unreasonable, to buy exhaust from Banks ?

I totally struck out with them. If someone had a connection it might happen, same for marine diesel in Texas, they want to sell their motors, not help someone else build one.
They are not really that hard to build but like most of this one off stuff, your done by the time you figure out how to streamline the job.

I think Kid had someone in Calif who would cast them but he needed volume.

I recently committed to ordering 2 of those Banks marine intakes with the Cupronickel heat exchanges at $4500 each, and they told me NO on the exhaust manifolds. I don't believe they actually have anything made up to sell. Same answer from the TX boys, not interested in selling any custom pieces alone.

In a couple pics and videos from Banks, you can see he's using Nicson jet boat manifolds on the Duramax setup. Closer looks shows an adapter plate between the head and manifold. So I did a little asking around, seems 392 HEMI shares similar port shape and dimensions. If that's correct, you can pick up those Nicson cast aluminum manifolds used off eBay for a couple hundred and likely be running for well under a grand. For fresh water use only of course..

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As Hoodoo mentioned I've worked with another Dmax boat owner on casting some manifolds in aluminum or stainless steel. We could 3D print the molds, then cast them as needed. But that first set was quoted at about 10k, so need to sell more than a couple.

That leaves us with custom SS headers or log style manifolds as the reasonable choice. After checking out pricing from CMI, and returning the set built by a small independent shop, my friend in Cali ask me to build a set. So I followed the approach Hoodoo took with the simple log design header.

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More on these next.

Interesting.

I was referring to these from Banks.
Pics: http://banksmarine.com/

And on video:
https://www.youtube.com/watch?v=M32tIPCchTA

Yeah those are what I ask about. Same intakes I ordered also. Think I got the last pair of them if it tells ya anything..

Since choices for good water cooled 6.6L Duramax manifolds or headers can be counted on one hand with several missing fingers, I've attempted to find a good SS tig welder to take on this task. First I contacted the marine exhaust pro's, where prices came in between 6-9k per set. Next checked with a couple big welding shops that specialized in stainless, they all passed.

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Finally I found a local welding shop who submitted a reasonable quote, if I supplied all materials and flanges including the mandrel bend tubes. After designing flanges in SolidWorks, getting those waterjet cut and purchasing all the tubing, I dropped everything off to the welder. Forty five days later with only about 20% complete, they bailed on the job... Luckily a professional welder friend of mine stepped in and helped finish the prototype set. Total cost on this set came in at $3500, only $500 over budget.

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I chose to go with all 316L stainless for these prototypes. After a bunch of reading I found that most cracks occur when two different grade metals are used. Sourcing matching radius mandrel bends of 2" & 2.5" 316L wasn't easy. Head and turbo flanges were cut from a single 1/2" thick 316L plate. Because there is no place for flexible bellows like the factory pipes, I chose a Vband configuration with custom made 316L flanges to connect the manifolds to the up pipes. This allows a little wiggle room on install, and a flex point for heat expansion when running. All the 1/2" NPT water ports and 1/8" NPT EGT sensor ports are also 316L SS.

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Learned a lot from building that first set. Making a couple design changes to the manifolds that should cut time and labor cost by about 10 hours or so. I'm getting ready to start on two more sets, so if anyone's interested in them let me know soon. I have a couple new bids on building these, but am also always open to suggestions.

Few more pics for anyone who wants to see what the jacketed or tube in tube process entails. Basically figure how long you think it should take and double it...

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Installed and plumbed on the test engine.

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Believe Hoodoo may some good pics of his custom set being built to share also.

Have you tried this company?

www.mesamarine.com

Believe I spoke with them couple year ago about building them. I'll hit them up next week.