[KaBoom1701]

First, a quick overview of how the system works

It is basically electrical control over vacuum actuation. The engine supplies vacuum to the system, the vacuum is stored in a tank to cover periods of low or no engine vacuum (WOT and start up). A check valve is upstream of the tank to keep the tank from dumping vacuum back to the intake manifold when there is no vacuum source. Electrical control comes from magic boxes sensing everything and deciding when to open and close Q15 (exhaust flow control valve).

The Camaro NPP factory system is programed to be open at idle, close about 1,500-2,000 rpm during normal driving and be open at > ~75-80% throttle position. I don’t have one to verify, but I believe the Corvette programing is different (closed at idle).

The bellow picture shows the vacuum lines, storage tank, control valve and actuator. The funny thing about my vacuum tank, it has “top” marked on it that is on the bottom. The tank is the black box on the right with a single vacuum connection, the control valve is protected by the Tetris shaped cover just to the left of the tank and the actuator is the round object attached to the output of the muffler. There are 2 actuators, one for each muffler. The control valve receives a 12v input to open vacuum to the actuator, when no 12v is present it dumps vacuum from the actuator but does not dump vacuum from the tank.