High flow exhaust Manifolds?

Interestingly the only factory manifolds they didn't test on that 300 Magnum, were Magnum manifolds.

Wonder why?


The engine they test with was a crate engine so it didn’t come with manifolds, guess they didn’t have any laying around to try, but I have seen another shoot out and they about the same as 340, they figured the best combo was one of the 340”s and one of the magnum”s I forget which ones.