Yeah, that one kinda came out of nowhere.
Here's my thoughts on the matter, though. You can never be "finished" because once you finish the stock motor you can swap a bigger one.
You can be "finished" to the point where it's barely able to be street driven. The idea is to burn more fuel to make power, usually decent turbo or supercharger kits will come with better injectors in the first place. The fuel rail doesn't necessarily need to be swapped out unless you're going for broke. You just have to know what the weak points and strengths are on the car. For instance, the coil pack on the Focus is proven good for 350+ whp, yet some people still insist on changing it out and spending another $300 for cars that barely have anything done to them.
It doesn't stop at your list, you could do a port/polish, or a new head with a valve job. You could add some insane overlapping cams. You could increase the compression ratio. You could upgrade to an even bigger exhaust which will make a turbo sing. You would at least need some kind of exhaust cause there's no point in modding only the intake side and having a huge bottleneck out the other side of the engine. With all that work done, an exhaust would add so much power and responsiveness it wouldn't even be funny.