The stock motor hardware is pretty tapped out straight from Ford. Reliable power in the range you're talking about requires great expense in the form of a built motor. You might find that you don't enjoy the trade-offs required in terms of noise/harshness of the driving experience, or peaky power, or fuel economy, or you might find that all that power doesn't make this platform more enjoyable.
This is the party-pooper opinion but if you want that much power reliably, start with a different car that comes from the factory with the power you're after. It will be engineered to work well as a system and likely cost you less in the end. Full disclosure - my car is stock, I haven't built any EcoBoost motors, and I am painting with broad strokes based on casual reading of the forum.