performer rpm vs airgap horsepower

i searched everywhere but cant find the article in hot rod magazine, any suggestions? also, this thread is kind of useless, as i found out from the seller the intake for sale was a chevy intake:angryfir:. so for now i will just use the strip-dom i have. also, i read some article a long time ago that said there was really a 5hp difference between the rpm and airgap. but i just wanted to know if somebody knew the hp difference from dyno experience or saw a newer article. thanks all.:hello2: