Its ALL in the ability to flow MOORRRREEEEE fuel.
I am able to make 400 whp on high octane gas, but because E85 requires 30% fuel to make the same power levels, I am limited by the max fuel that I can flow.
Now if I had larger injectors, say 1200cc, then I would be able to go OVER 400whp because I could turn up the boost AND not run out of fuel.