Keep in mind, once you goto 2.2 L, there isn't much more you can do besides raise compression MORE (Not streetable).

That's why I said if you want more than 350 HP, go turbo. Less than 350 HP in this situation, stay all engine.

Think of what you want in the end. Once you have an all-engine set up, it's going to hurt the bank even more to go turbo, so decide now.