If you turn the boost controller off that will show you what the restrictor ring is holding the boost to. The boost controller can't lower the boost, it can only raise it, so if you turn it off the car will then boost to it's "natural" level. The level will be dictated by the restrictor ring, ergo telling you approx what size it is.
The problem with split vac lines will mean you will be potentially overworking, over speeding the turbo. It's running on borrowed time. Think about it as running the car at 1.4bar, 1.2bar is what the manifold sees while 0.2bar is lost through the leak. It might not go straight away but it WILL go eventually as 1.2 is the maximum safe limit for the turbos to be producing. It would be better to drop the boost down so that you aren't chancing running the turbos outwith their efficiency.
Last thing you want to do is lose a set of turbos over a split vac line.
You will probably find you are restricting it a little too much, I am at the moment too as my EGTs are a little high. My natural boost is around 0.9 with the RR in, I want to have it 1.0 in low gears and around 1.1 in the higher gears, I'll need to attack it with a dremmel to get it up to spec. That way I am only forcing another 0.1/0.2 out of the system, from it's natural boost level, therefor keeping the EGTs at a safer level.
If you need any help give me a shout