What about exhaust manifolds? To the best of my knowledge Dan has been saying all along this will require Gen IV style headers, or OE Gen IV manifolds to work with these heads...is that true? If so, that's quite a "hidden" cost to this upgrade...
You will
still need headers. The mounting flanges of Gen-1/2/3 aren't even remotely close to a Gen-4. The bolts are nearly 45* offset on every single hole. That's a fairly hefty additional expense, and I have a hard time believing you will see the numbers they claim without using
headers, not just the OE manifolds. Those manifolds are good, but not
that good. Just ask yourself- how would a head package that uses the same parts as a production Gen-4 make considerably more horsepower than the production version, with a smaller camshaft? The Gen-3 cam is actually smaller than the Gen-4. It just doesn't make sense unless you are comparing a Stock production Gen-4 to a Header/Exhaust Gen-3/Gen-4 Conversion type package. Even after that, I can barely see those numbers being possible in that scenario on a production Gen-3 Cam. Someone who bolts this together with Gen-4 manifolds on a stock Gen-3 Cam as would be "expected" by how the package is being marketed should expect to see lower numbers than a stock Gen-4. The exact same argument could be made even if there was some way of bolting Gen-3 manifolds to Gen-4 heads.
All I am saying, is this is being marketed as "complete" and "650 Horsepower", when it really isn't from what I am seeing, and is slightly misleading in terms of what expectations people will have at this point. That is not to say that this isn't an excellent starting point, but I see mass confusion on the horizon here.
Unless someone would like to explain to me how you make a flange designed to fit this:
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To bolt up to this:
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A slight problem, no?