I have been informed that for my Nordic Stage 3 ECU I need to run at a basic boost of .45bar/6.5psi. Unfortunatley with this setting I get boost that fluctuates between 1.1 and 1.4 bar below 4krpm which is very anhoying. After observing the behaviour of my boost needle it would seem that the boost is rising rapidly to the 1.4bar limit and then suddenly cutting back to 1.1 bar before pushing up again and then cutting back etc. Above 4krpm it holds a steady 1.4 bar so it would seem that the fueling is not inadequate and neither is the WG being blown open from within. What I think is happening is that the very free flowing IC and exhaust is creating faster boost rise than the ECU expects and when it opens the BPC to divert pressure to the actuator it dumps too much pressure? I fitted an external helper spring to the WG and this raised base boost to .7bar/10psi. All conventional wisdom would suggest that this will create boost spikes ( which I already have anyway if I punch the pedal in 3/4/5) but what seems to happen is that once the ECU has learnt the limit it is holding higher boost with much more stability - 1.3-1.4bar. In the old days of c900 APC tunning it would be recommended that base boost is set to 1/2 the max boost so why do ECU tuners (except Abbott) recommend a base boost at stock settings. I still have the full WG movement and if I was encountering any knock the ECU would lower the boost by holding the BPC open to the WG? The BPC tests good, I'm using 97RON fuel, DI is new, plugs are new and correctly gapped. Any comments as I'm still not entierly comfortable deviating from Nordic guidelines.