All Turbo's...after 100K kms should be overhauled......especially the ceramic type ones Nissan used.
This is even to long if the car has had a lead foot at the wheel.
My assumption is that all gtr32's have had some tinkering in the odometer readings....making for more$$$$
at the auctions. This also goes for a lot of other imports.
Getting back to your boost and realiability.....................
1 Bar on standard turbo's on a gtr is fine if the turbo's are new.......
They can support only this much...dialling them up higher does not improve anything.
On the other hand ,if you are sure your turbo's have not been driven hard ,
have been on your car since the car was new and your odometer reading is correct
run 1 bar only .
Don't forget...preventian is better than the cure....especially when it comes to a RB26.
Hope I have been of some help.