Need help: Greddy Profec B Spec II
 

I'm a little confuse about "SET GAIN" (START BOOST)

I've google it, some say set this as desire boost -4psi; other say set this same as psi as the wastegate spring. :confused:

can anyone confirm about this

Start boost is the pressure at which the controller starts to actuate the wastegate. Below this pressure the solenoid is closed and thus the wastegate will be closed. You usually want to set this about 6 psi below your desired maximum boost.

You can play with this. Set the "Set Gain" as close to the target boost as you can without getting a boost spike (boost exceeding target boost before settling back down to target boost) in order to get the quickest spool up. On my car that is about 2.5-3 psi before my target boost.