Why aren't headers readily available?

[DennisG01]

With my engine out, I've been taking advantage of the space/access and cleaning/replacing certain things while I have the opportunity (front pump seal, motor mounts, etc). But, I got to wondering about replacing the exhaust manifolds, although they do seem to be in good shape. If I would decide to do that, I would only do it if the replacements were of better quality/performance - like a pair of headers. I can't find find any for the 6.5... Is it because of the turbo and headers wouldn't make that much of a difference, anyways?

[DmaxMaverick]

True. Turbo's and headers don't really go together. The purpose of headers in the first place is exhaust scavenging. This only works on N/A engines. There may be some gain with headers and a turbo, but I doubt it would be noticeable. You may see a marginal gain on a dyno, but that's not practical for the populous. Also, headers generally increase underhood and radiant temps, which is something most folks try to minimize with these trucks. Headers also take up more space, and space is a premium. You could use Hmmwv headers, which aren't really headers, but pretty close, and would be easier to connect up the the rest of the plumbing.

That said, I like the idea of headers with a turbo engine. I would prefer to use a gang-type header (as opposed to a collector type), like you find on OEM high performance cars. More compact than traditional headers, and more free flowing than the standard manifold. The HMMWV headers are somewhat gang-type. The Banks intake design for the twin turbo Duramax looks like it would be a good template for a gang type exhaust header. I have considered fabricating the intake and exhaust for my 1985 Blazer restoration, with this in mind, turbo or not.