Unfortunately they don't say which 360 manifold was used for the test?? The 360 manifolds shown in the pics of this article are some of the smallest 360 manifolds made. As opposed to the 360 manifolds that I sell which have an exhaust exit hole the same size as the HP 340 manifolds.
As you can see in this pic below, the 360 magnum (the correct one) has a humongous exhaust hole compared the 318 and the "regular" 360 manifolds.
