Saw some comment about how easy and cheap it would be to make significantly more power from the new M3/4's engine, and was wondering how true this statement might be. Found some numbers: max. boost from the factory is ~19 psi. Seems pretty high for an OEM application, and was wondering what the highest factory pressure is for any passenger car, up to this point.

I assume OPPO knows.

Maximum OEM Turbo PSI?

"At the heart of BMW M division's new twin-turbocharged 3.0-liter inline six-cylinder, which is mounted longitudinally, is a patented induction process that uses two low-inertia turbochargers. Eschewing both twin-scroll and variable vane geometry, the IHI units provide a relatively conservative maximum boost pressure of just 18.9 psi."

For those of you experienced with "overboosting" (like overclocking?) turbo-ed engines, what pressure do you expect this engine to take comfortably, while maintaining reliability? Too early to tell?

Can an aluminum block handle less pressure than a cast iron one, by nature, or is that no longer the case?