I don't know about dyno results or intake shapes, but after reading the above posts, I took the venturi (is that what it's called?) out of the carb, then tuned it for the larger intake hole. The speed and power are insane. After doing this, I could nail the throttle from a dead and the car would do a 360. The top end was noticeably faster.

I think I'm going to take the smallest insert and chuck it up in my lathe and turn the inside out at an angle. Perhaps, starting out at the widest possible opening at the top and then tapering to the size of the intake at the bottom will result in an air "acceleration" effect. Who knows, I don't have a degree in engineering, but I may stumble onto something. As far as the 9mm minimum requirement, do they go by the largest diameter of the opening or the smallest?