Headers vs 340 manifolds

I remember @IQ52 (Jim Laroy) did a dyno comparison between stock and HP manifolds years ago and found basically no difference. I believe Laroy Racing Engines knows what they're doing.

Here's what everyone is missing from my argument. Removing ALL variables.....in other words, NO engine, no NUTHIN, just long tube headers and manifolds on the flow bench. Headers win every time. Most people with the sense God gave a billy goat, if building an engine from the rip with headers WILL BUILD the engine to take advantage of them. In other words, single pattern cam, bigger than stock intake and carburetor possibly better heads, more compression and so on. Even if you have an existing build and just "slap some on" you WILL SEE more power as long as you TUNE for the headers. It's all in the tune. If you cannot and don't tune, it's entirely possible you won't see a difference. But that would be kinda stupid, wouldn't it?