So, I need to update this thread, hopefully people will read down to here if they want to do this, since I can't edit my original post..

I realized while ripping out all my old AFC neo crap that at atmospheric pressure (car turned off), the voltage at the MAP was actually more like 3.65v, NOT 4.7v.

I never really found the pressure vs voltage curve for the MAP sensor, but I think if you do this you'll have better results with a 4.3, or even less for the Zener diode.

I'm working on megasquirt on my car anyway, so this is useless, and so far I have only $300 in my MS setup, and the car runs. To see videos of my conversion, search "Evan's Megasquirt Build" on youtube, I'm documenting the process there.