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In simple terms, you could compare a couple different applications.

If you were building a race engine, designed to produce maximum power, you would want to have maximum compression that the fuel allows, and you would want to run it at maximum RPMs, so you would need to have massive ports, valves, manifold runners, a high lift long duration cam holding the valves open as long as possible, a huge carburetor to allow for max airflow, and and headers to try to clear the gasses as quickly as possible. If any of these restrict the air volumn, you get whipped by the guy in the next lane. Also other basic things are different. The spark plug has to fire a little sooner, since things are happening so fast. The engine needs more fuel for the amount of air, since you make more power if you burn more fuel. That fuel needs to be higher octane, since the cylinder pressure is much greater.

On the other end of the spectrum, you have low octane pump gas, an engine that needs to start under the worst conditions. It will be operated at low RPMs most of the time, must produce torque down low when the light turns green and you are coming off of idle conditions, and must get good mileage and be reliable. If any one part of this whole picture is too excessive, you lose lots of horsepower.

Some of the problems with the race motor in a street car are that the air is now flowing very slow through all of those big passages. The vaporized fuel will not stay vaporized, and the fuel mixture is far too rich for idle conditions. If it stays running at all it will be fouling spark plugs, stalling out, be very very weak at low RPMs. You also will not be able to run it on pump gas, and in a race motor the fuel mixture will explode from pressure, before the piston gets to the top of the cylinder, and the spark plug fires. This is called detonation, and destroys engines!

Just like the race motor, if your street engine has one element that does not work in sync with the others, it will not work the way you wanted it to.

The point of all of this is that you need the right combination of parts, to achieve everything working at the same RPM range, for your desired operating conditions. If you have one important element is too much.....or too little....the engine will lose power, or have problems.

You need to look at the weight of the car, the driveline type, gearing, tire diameter, what you will use the car for, engine size, fuel type, and other things, then try to design a combination that works to perfection under those conditions.

You are making a good choice in asking people who have "been there" and "done that". Those are the ones you want to take advise from.