the boost control kit is actually 3 seperate parts, which you can buy from nengun seperately
the boost control kit loom
the map sensor
the solenoid
the map sensor is the same as the AVC-R sensor
the solenoid is the same as the AVC-R solenoid
you can use any solenoid you want as long as its 12v (actually, maybe its 5v?)
the powerfc simply switches the ground wire on/off to control boost duty - it wont know its a non legit apexi solenoid so you should be fine
the loom is a white connector which plugs into the boost kit port and then runs to the map sensor
there are there wires on this loom and it is for the map sensor only (ground, signal and power)
the boost solenoid gets power 12v from anywhere and the switched ground wire MUST come from pin 25 on the ECU loom (from memory its 25, it will say WASATEGATE SOLENOID) ie the stock GTST dual stage boost wire
you can plug in the boost kit LOOM and run up the map sensor and plug it in and the hand controller with display boost pressure
its only when you turn ON the boost kit that the boost profiles are enabled and it starts switching the solenoid on/off to reach target etc
so if the boost kit is OFF and you plug in the white socket and run up the map sensor your hand controller will show boost pressure, BOST will have a value in ETC. SENSOR SW CHECK and all will be good.