As myRB25DETT said; The consensus is that any more than 1-bar is risking destruction due to over-speeding the ceramic turbine, causing either separation from the steel shaft, or the blades to break.
(and bear in mind that 14psi @ the manifold is close to 17psi @ the compressor if you're still using the stock SMIC)
To double-clarify the construction of your snail: - nylon compressor, steel shaft, ceramic composite turbine.
I've heard that replacing the nylon compressor with an alloy one is a sensible thing to do as the nylon blades have a tendency to flex, and eventually break at raised boost levels.
So...
Keep the boost sensible, and the stock unit will last fine. If you want 'more' then an upgrade is desired (or be prepared to replace the stock unit every time you blow it up).
My 2.5c worth (the aussie dollar is pretty good right now...)