CM870 VGT Actuator

[Lonestar10]

My dads 2007 T600KW CM870 popped up with some codes for the VGT air actuator and it wasnt working correctly so it was replaced. New OEM air actuator put on now he says his boost doesnt go as high as it used to when pulling only gets up around 30-32 where it used to run 35-37. Truck is a bone stock cummins 500/1650 Tune only thing changed was the air actuator. turbo was replaced last year in the spring.


any ideas? thanks for any info!