Magnum Exhaust Manifolds in an A Body

Jim Laroy and company did somewhat of a manifold shootout years ago and posted that there is very little IF ANY difference between stone stock manifolds and HP manifolds. As usual, they had the detractors and nonbelievers coming out in droves, but they're the ones with the dyno. If I was worried about ANY kind of performance, I'd be lookin at headers and not futzing around with cast iron paperweights.