Actually, the stock injectors will hold up to 6lbs of boost, quite nicely. They won't max out the duty cycle at that setting.

Not to mention that at only 6lbs, with an N/A motor anyway, you'd naturally be making more power.

Timing isn't a huge factor, just don't run with it advanced all the way. He's not disabling the knock sensor, so the computer will retard at the first sign of pinging.

The factory fuel pump can still be used. Again, with the factory fuel injectors, that pump can easily, and reliably run at the pressures needed.

The Supercharged X's aren't a marvel of tuning science. They're just a bit lower compression with a slightly different fuel mapping. I'm sure there are some other minor differences, but Nissans have always been notoriously easy to boost, with the exception of the 25QR motor, and do so reliably.

It's not rocket science, just a Supercharger.