piston questions

what if i'm a penny pinching nickel dick that doesn't care about 20hp at 6000rpm?
Well, I am too but I won’t give up what the RPM will do for the cost difference. The rpm is better at every point in the graph. They match in a few spots but the m1 is never better and in some places the rpm is 20lb/ft better. And that was on a 350hp ish engine. On more engine the gain will be more. The list goes like this;

Best to worst
1. RPM Air gap 365/423
2. M1 dual plane 350/400
3. China gap. I’ll have to look for the numbers.