I have the Double decat but 3" with Restrictor ring in place, also have the Blitz NUR Spec R. I use the Blitz SBC meter and Power iD as you can see from my signature. After I had just these mod's fitted the car was a totally different beast.
If you have no boost controller installed then the boost can get up to 1.2-1.3 bar - but depending on which restrictor ring you have it should be kept below 1.2 bar.
The second Turbo should start to spool around 3900rpm and be on full by 4500rpm.
From 0-100mph, the boost will vary on speed, 1st gear dont do much, 2nd maybe hit 1.1 bar but 3rd is where it creeps, will go up as far as your system lets it.
HTH
Hornet