Just got a 2007 St3 really mint car. It boosts to the red everytime and drives perfectly. Had it been chipped? Is it supposed to boost 1.2 bar? It seams to boost hard then the boost drops off at 4000rpm...the gauge still shows 1.2 bar but the car isn't as fast. Feels like it bleeding of the boost or holding back etc. Any ideas??? As I said it physically drives perfectly. Thanks lads.

 

If it's going to the red each time it's been mapped. They usually peak at 3/4 then drop off to over half.

Is there any whistling noises? Could be a number of things from a leak to boost solenoid or oil diaphragm.

 

Check the boost solenoid as they are a known weak point and would cause the lose of boost but tend to cause a spike on lift off as well

 

as above, sounds like the boost solenoid to me.