Well....
Ok.... Here's what I know.
I've run .9 bar now for 6 months about 50% of the time and nothings blown up.
Only problem is the damn hose from the manifold to the boost gauges (2 of em) keeps splitting or falling off. Prob cos its a 10 year old bit of rubber. I keep cutting off the split part and I have now run out of hose. Time for a new one.
There is a THEORY that the RB20DET we know and love has a steel headgasket as standard. I have heard this from several knowledgeable sources, but am not gonna be the one to test it personally.
RE the turbo, I've hit 1.1 a few times whilst setting up the controller, and while it still runs fine, My arse was a twitchin'.
I've got a spare turbo here in the flat and I must say it spins VERY freely, which makes me curious about what bearings are in it. And the turbine doesn't look too ceramic to me either.
Again, thats my hint and theory, which could be wrong.
The stock R32 blower will handle more than an R33 I have also heard, as will the head and gaskets. Dunno why, but there you have it. 500cc smaller engine, but more bang!
Don't use a bleed valve, get a decent controller. I use a Profec 'A'. Not as user friendly or easy to set up as the 'B', but better if you get it to 'learn' properly.
I have also heard from some guys downunder that over 1 bar is a 'safe' limit. Over that, they reckon bad things will happen in time unless your engine is PERFECTLY maintained, with super sweet quality oil etc.
At the end of the day, who knows whats in your car though. Is it standard mechanically? I've seen 8000rpm and slightly above and still no limiter. Standard ECU too. Likewise, .9 bar on standard ecu. With regular resets.
I richened things up a bit with an A'Pexi S-AFC just to be on the safe side, but haven't yet seen a boost/fuel cut.
Could waffle on and on, so I'll keep an eye on this thread and see if I can maybe help.
BTW... If you are setting it mechanically, try and do it on a cold day, or adjust her for the winter, cos while an electronic controller will set the boost regardless, a mechanical bleed adjustment on a hot summers day to .9 bar will lead to a bit more on a cold winters night I think you'll find. Denser air.
Hope some of this helps. There are so many urban myths about RB20 blocks I have heard that its kinda hard to distil some truth.