I told you on PM's. Injectors just provide more fuel. If you're running out of fuel (like from a turbo or something), larger injectors (and to an extent a fuel pressure regulator and fuel pump) will give you what you need. There's no reason to increase injector size if you don't need them.
As for the fuel rail, if you're replacing your injectors with another set of side feeds (like SR20det or WRX injectors) it should work no problem in the stock fuel rail. If you have top feeds, you'll need an aftermarket fuel rail.
Oh and you'll need some sort of fuel controller to tune the larger injectors or have your stock ecu retuned.