Years ago (maybe like 50) I had a factory 4 hole 383 manifold that I made into one big square hole. All blended and looking great. I thought it was working until I put on my two barrel manifold for winter driving. The two barrel was such a marked improvement in performance it was rather unbelievable.

My mechanic neighbor said something to the effect "did you think the factory guys were stupid?"

My only reply was to toss the manifold.