I've just had a custom exhaust fitted to the 9-3 and the guys at Topgear (Doncaster) put it on the rolling road. It hits 194bhp at 3300rpm then drops off abruptly. Boost is always too high though the actuator is set to a minimum. If I unplug the plug on the magnetic valve there is no change. Is it possible to test the valve off the car, since a fault could be in the ECU, wiring, vacuum system, etc?