just installed a new wastegate actuator , when give full throttle the boost spikes at 0.6 bar and then settles at 0.55bar (8psi) but after a while it just starts rising very slowly.I wasn't paying attention to my boost gauge and all of a sudden I had 0.65 bar.. What's the cause of this?
If i reduce my throttle just a tiny bit it goes back to 0.55 bar and stays there.

thanks