As I said. If you don't hear surge, then the pressure is being released from somewhere. Take some soapy water and spray down the engine while under idle. Rev the engine and watch where it bubbles up. In a completely sealed system the surge sound will be evident and on its way to causing damage. I have seen cars that run without BOVs and they survive for the above reason, and as I said b)they're running low boost c)have a long enough tract from the turbocharger to the throttle body (generally with an oversized intercooler) to absorb the pressure d)the compressor housing may also retain enough space to absorb the extra pressure.
I've always wondered why many people on this site seem to have lower figures than us here, suffer so much engine/turbo failure, and I think I might have found one of the reasons why.
Anyway to each their own. I my apologies if I offended any with my idiot comment, but any forced induction performance specialist would say the same. Its one of the basics of turbocharging.