@ 5000 RPM the cam solenoid is switched on, adjusting the valve timing, (only if the engine is under load though, wont do it just revving it). It also switches on the stock bleed valve (solenoid) in the waste gate actuator line to bleed some pressure off, (back into the low pressure side of your intake). The waste gate spring itself will limit boost top about 5 PSI, but bleeding some pressure off from the waste gate line gives you a little more boost (@5000 rpm). The amount of bleed is controlled by the size of the orificew in the solenoid.