I thing that whether or not someone experiences overboost conditions, fault codes, or whatever, at 4.5 turns is dependent on what the starting, factory setting was for that individual car.

In my case, for instance, I had no pressure on the arm whatsoever in factory trim, so that my 4.5 turns is going to increase boost levels less than someone who had a correct factory setting of 1.8 psi for the actuator diaphram. In my case the adjustment has been excellent, increasing my throttle responsiveness, while prducing zero fault codes, and with the boost level needle never extending beyond the white.

The difference I feel is pretty close , in degree, to what I feel if I disconnect the battery for a period of time...When I reconnect, I, as well as others, have commented that we feel a pretty decent increase in throttle response, until the settings are 'relearned'.

I dont know whether the fact that I'm running the IPD ecu with higher boost levels at the max, makes it easier for this adjustment to run well on my system or not, but its a possibility that it works better on a system with a max boost of 14 psi than the stock system with around 10 psi.