You know I am not sure exactly. I had the same problem and still may I am not sure. I tore my truck down to do head studs because I wasnt sure if they were blown or not. Well my head gaskets werent blown and I am finishing putting the truck back together so we'll see if I still have the same problem. I noticed that it did it when ambient Temps got over 80F. I am thinking it is a sensor that was dirty. I know things can get screwy when sensors are dirty. I would start with MAF sensor cleaner and clean your MAF sensor, MAP sensor, and EBP sensor. Hopefully more folks will chime in.
my truck only cruises at 10 psi and at wide open its well over 50. oh wait, I have twins. remember boost is derived from heat and pressure, your cruising boost pressure does not bother me, your wot psi doesn't bother me. we need way more info to tell you if you actually have a problem
Right 7-8 psi while cruising at ~2000 rpms, which is just over 70 mph on stock tire and gears, is what I would say it should be. But TEN?? (10 psi) at only 60-65 mph with stock turbo and injectors?? That seems high to me and I would be very curious to know what would cause that.
Honestly...you're worried about a boost reading that seems 2-3psi higher than you think it should be? I really wouldn't be worried about it. I have the same non vgt turbo Extended power had(64/71/70) and i'm seeing around 7-10psi cruising between 65-70mph depending how hot it is outside. A VGT turbo will stay spooled way better than a non vgt turbo. So for you to be at around 10psi while cruising at that speed, doesn't bother me one bit and seems fine to me.
ground slope can be invisible to the eye and have a very significant effect on boost levels, likewise as has been noted so can wind. there are far too many unmeasured variables to get your knickers all knotted up over such a small boost variation. that said if anything i would suspect the turbo vanes are very slightly sticky. after a camping trip in the mountains with my truck it seemed to pull slightly less boost and not run the engine fan nearly as much.(much large hills with curves, so very many full throttle to full coasting cycles with lots of heat=vanes really got exercised)
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