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All those tests are around 10 hp/lbs apart. Not realistic to me.



So what, you think they faked the results? If the results are close, it does show on a stockish 383 that the manifold isn't the bottleneck. On part 2 where they bolt on the cnc ported aftermarket heads, the results do change a good bit. Even then, it's not an extreme, rpm screamer of a build.