Nobody's mentioned compression ratios yet. Lower the compression, and your engine can handle more boost, but it will make less hp until your turbo spools.

If you're running 9:1 compression, at 19 PSI... high-octane pump gas will start to knock unless you have a REALLY efficient intercooler. Detonation will destroy a heavily boosted D-series almost instantaneously. A factory D-series rod will fold over like a wet noodle at a little more than half that much, so just treat that as an interesting fact. Running lean can cause detonation at any boost level, so your fuel trims need to be rock-solid 14.7:1 throught the whole power band at WOT if you're going to push it over 6-8 PSI on stock internals.