Years ago in '68 I opened up the 4 individual holes in a stock '63 Dodge 383 and made an open plenum. Put it on and ran the whole summer with it. When I put a two barrel carb and manifold back on it for the winter I found that to have much more performance than the 4 barrel, seat of the pants kind of performance gain. I threw the modified 4 barrel away, it was a dog. I'd watch what you do, it didn't work out for me.