@ GTP900, The link below explains the different locations one could install the nozzles.
http://www.alcohol-injection.com/en/...jection-nozzle
I went pre-IAT based on the info below.
from DevilsOwn website:
"Most computer controlled engines have an intake air temperature (IAT) sensor. This sensor monitors the temperature of the air going into the motor. The reason for putting it before the IAT sensor is because it will see the cooler temps and the engine will advance timing, allowing for more power. Also placing the injection nozzle as far from the cylinders/air intake sensor as possible, it allows for the water/methanol mixture to be better absorbed into the intake air charge. This allows for great distribution to each cylinder. This post intercooler nozzle location should be the primary nozzle location to be considered for most users.
In theory, since the air charge will be mixed for a longer distance, and therefore time, allowing for the moisture to be absorbed by the air, creating the coolest possible air charge going into the cylinders. Water/methanol molecules from a nozzle located here have more time to be absorbed by the intake charge exiting the intercooler before making it into the combustion chamber."