was out in the series 1 tonight ,driving reasonably hard in 3rd gear,changed into 4th and boost wouldnt build for ages.only running 10 psi so theres not much lag.i've recently stuck a bailey twin piston dump valve on it,as the forge motorsport one fitted previously was sticking.before the forge started playing up boost was 12psi.wnen bailey fitted it whent down to 10.(although was driving perfectly until tonight.its been chipped ,has a grs chargecooler and a kent cvh 35 cam,the boost was turned down to 12psi by prev.owner ).any ideas whats wrong??

 

What hoses have you got on there? no air leak anywhere, could be boosting then dropping straight away.. just a thought

 

its got samco's on it,it boosts up straightaway in 3rd gear just seems to bog down in 4th.maybe the actuator needes a look.