Hi there i have a astra coupe torbo its comin up to 57k its been running fine but the past few weeks it has lost power and now in every gear the turbo whistles under load. i,ve looked at the intercooler pipes and they seem ok it feels like turbo is comin in and out under load the whistle comes in aroud 3500rpm then goes around 5500 it dose this in every gear it only used to do it in 1st n 2nd but dose it all the time now. Not sure if there is somthing rong with the turbo can anyone help.