Not to mention a bigger turbo can flow a lot more air than a smaller k03. More air can be moved through the engine so you can add more fuel and everything else to make more power.
Well buergi's point is that the VE of the motor is the main limiting factor... for a given density of air and pressure, the same amount of air mass will flow through a motor, regardless of the turbo.
That said, backpressure and IAT's do have an effect.
