I would find it hard to imagine that anyone is manufacturing a turbo petrol engine without some form of bypass valve. Just because you don't hear it doesn't mean it's not there. The MPS is a case in point. The average wally wouldn't know if it was there or not as it is almost inaudible. The reason is that as the throttle plate closes, the boosted air has nowhere to go and the backpressure wave will feed back to the turbo, inducing some form of stall or incipient stall. In extreme cases it can be damaging, by stalling the compressor repeatedly. Diesel engines do not have a throttle plate so the consideration is different.
Anyway, my last post remains relevant. In a well-meaning attempt to assist you, I explained why you might need an adjustable BOV if you are having the problems you are experiencing, all else being equal. I didn't suggest that you would destroy your engine without one, and I'm not sure why you would assume I might say that, particularly in view of the point I make above where I know that except in rare cases, petrol turbo engines all have some means of dumping boost to protect the turbo, variously referred to as Bypass valves, Blow-off valves or Dump valves. They all do much the same job. However, the type and the name by which it is known tends to vary across industries and whether the engines to which they are fitted are more or less constant speed or not (e.g. aircraft engines).
The only other comment I'll make, again, for I have written this previously on this site, is that more BS is talked about BOVs than any other component in a turbo engine. For a simple device that is intended to do only one job, it is the most misunderstood item and principle since the abacus, and is blamed for more problems or espoused as the cure for more mechanical and performance ills and as the source of more mythical horsepower than Tiger Balm suppositories.
CP_e Standback & PNP; CP_e 3" SS Downpipe; Corksport FMIC with Top-mount K&N filter & OEM Ram CAI; Turbosmart BOV; Dashhawk; Prosport Boost Guage; JBR solid shift bushes; DBA 4000 Wiper-Slot front rotors; Hawk Ferro-Carbon HPS Street front brake pads (@ 69,000km); Sumitomo HTRZIII's in 225/45 x 18