problem you have with a de+t setup is that the compression ratio is much higher therefore more likely to melt a piston with savage det. The head on the DE is actually better (larger cams and throttle body) so in theory you should be able to get more power.
Unfortunately the block isnt as well suited to runnig boost. The compression ratio is much higher 9.5:1 or 10:1 depending on engine year and spec with high comp pistons and no oil squirter's on the pistons to keep everything cool.
At that PSI you should be ok, problems happen when you start to go beyond 7psi as a rule of thumb but there are people who have run higher psi with great results. higher compression means that for the boost level you will make more response and more hp than the equivalent boost on det engine. Sounds good, but in reality its more likely that things will go pop.
My advice if you want to run more boost is buy a DET block from a VVT sr and chuck your head on it. you will get away with using the de ignition and loom if thats what your using already but wouldnt push that setup past 1.0 bar because the de ignition really isnt up to the task (providing its a T28 or T28r turbo) and thats the reason Nissan use coilpacks on the DET sr's.
If you want to up the boost with your setup you would really need to take it to your mapper and do it on a rolling road while getting it mapped and turn it up a little at a time. but again, i would save your cash and do a block swap to be safe.
Do not just up the boost on your car please, it will end in tears if you mess it up.