Loss off power but no SVS light

[Megatron1968]

Hello can anyone help please I have lost boost power. when on motorway I put car in 3rd gear there's no power I put pedal to the floor it slowly picks up but no boost there  but I have no SVS light on. Could it be the boost pipe even tho I have no SVS light on 

[Vauxhall Owners Club]

More than likely the turbo variable vanes have gummed up with carbon, especially if the car hasn't had a good blast for ages this tends to happen