[Richard L]

I think the MF2 can take over from 1 atoms upwards.

There are several ways to stop the OE ECU seeing the boost pressure.
1. By ECU reflash (you need a tool)
2. By putting a MAP sensor clamp. ie, it limits the MAP sensor signal from going above a preset voltage.

I think the second method is easier to do.

I have also notice that you are going to use a PPS system (progressive pump speed) for methanol injection.... few comments below:
1. The PPS system do not have enough dynamic range to cover a supercharged engine. a 50-250psi (pressure change) only give a flow range of 1: x2.3
2. Supercharge has very fast load change compared to a turbocharger. the PPS system is too slow to react to an instant throttle change dus to the rotating mass of the pump motor
3. The meth flow is not linear to pressure change
4. PPS system without an inline valve will dribble after switching off due to the pump running on.