For the EC2 I would recommend putting the MAP sensing port out in the plenum before the runners.  The best reason I can give is that that’s where Tracy puts it, and the programming in the unit assumes that’s where it is. You want it to see essentially ambient pressure at WOT.

 I have a 3-barrel TWM TB on a very short manifold, and the sensor ports just downstream from the butterflys.  The “runners” are effectively upstream, so there is pressure drop before the sensor ports.  At high RPM (6000) and WOT the MAP sensed is about 3.5”Hg less than the ambient pressure.

Also close to the ports on the engine there is fairly severe pulsing, so I had to add some volume and restriction to smooth (analogous to an RC filter in electronics) the pressure read at the controller; and the MAP pressure reference to the fuel pressure regulator.  Before doing that the needle on a pressure gauge at the fuel rail would ‘buzz’ over a range of about 10 psi.

Al