Richard Holdener did an air gap vs 360 4bbl on a mild 360, it had decent gain's mainly in the middle of the powerband, the top and bottom was very similar power wise. Start's around 8.20
Engine masters dis dual plane M1 vs Airgap pick up 20 hp on a mild magnum, guessing making the M1 similar to stock intake too.
I know that a dyno is a very valuable tool. Great info can be gathered. I know you quote/post richard a lot. I'm strange, I like boots on the ground. AKA - ET slips. I still say that at the end of the day, the response is different from Dyno vs Track. Not saying he is wrong with his results, of course. Andy Wood did a great video on "the dyno is not the track". He found out after having mixed boss perfectly tuned on the dyno, it needed retuned at the track.