I usually had it coming in at around 15 psi. However now that I am using straight methanol, starting to get into a groove with the tuning, and power output is steadily going up, the turn on point had to go down to 10-11 psi. Everyone's vehicle (and combo) is different, whether intercooled or not. Its going to take some experimenting to find out what yours likes. Most say to have it come on before KR.