You can, but is is a big waste of money. These are eye candy only. They do next to nothing for performance.
First, you need to think of your engine as an air pump. If your 1.8 liter engine had the perfect cylinder heads, perfect camshafts, largest possible valves, perfect intake manifold, at 6400 RPM, it can only flow about 200 CFM of air. I doubt you have these perfect engine components, so the engine flows considerably less, as much as 25% less. It's not as though you are feeding a big block V8 with a big Holley carburetor. So how much airflow do you really need?
Next, you need to examine the throttle body and the tube that connects it to the air filter housing. I will use my car as an example. The engine is a common multi port fuel injected, 3.1 liter V6. On this engine, if you measure the diameter of the throttle plate, it is 2.035 inches (52 millimeters). If you measure the diameter if the stock pipe that connects the throttle body to the air filter housing, it is 3 inches, (76 millimeters). Since the stock pipe connecting the throttle body to the air filter is already 50% larger than the throttle plate, adding an even larger pipe will not flow any more air than can already pass through the throttle bore. No real improvements here unless you also add a larger throttle body and enlarge the throttle opening in the intake manifold.
If you examine the air filter housing you will see that it draws its air from an opening in the radiator core support, drawing air from in front of the engine compartment. This air is already relatively cool. No gains found here.
The name "Cold Air Intake" is very misleading. On a cold air intake, even if it has some kind of intercooler, it will NOT cool the air any cooler than the ambient outside air temperature. Also consider that the air passes quickly between the air filter and the throttle body, too quickly to absorb any significant amount of heat. With a V8 engine, you gain about 1 horsepower for every 10 degrees Fahrenheit drop in temperature. Therefore, even if you could drop the incoming air 50 degrees, you gain a measly 5 horsepower. These gains are proportionately less on smaller 4 or 6 cylinder engines. So they are hardly worth the expense.
Another thing to consider is that your engine is equipped with an EGR (Exhaust Gas Recirculation) valve. This device dumps hot exhaust gas from the exhaust manifold, into the intake manifold. This exhaust gas is over 1000 degrees F. A cold air intake can't make a difference over this extremely hot gas. Your engine is tuned to operate with this so it is not a problem.
The air filter used in the cold air intake is the only component that may give you any real improvement. But with a late model fuel injected engine, avoid the ones that use the washable oiled gauze elements. If even the slightest amount of oil from the filter gets on your Mass Airflow Sensor, it will foul the sensor. This sensor is located in the tube between the throttle body and the air filter housing. If fouled, it will send erratic signals to the engine management computer. This will mess up your fuel / air mixture to the point that you could have even less power than you had before you added this component. If you already have one of these types of oiled air filter elements, you should clean the Mass Airflow Sensor with the correct cleaner every few months. Use Mass Airflow Sensor cleaner, and not carburetor cleaner, or you will destroy the sensor. Instead of the cold air intake, I would just simply add a low restriction air filter element.
For a little bit more than a cold air system, you can purchase a dry nitrous oxide system. For about $350 - $500, you can install a dry nitrous oxide kit that will add 50 - 75 horsepower to your Celica. This will give you performance gains you will actually notice. For a little over $500, you could install a wet nitrous system that could give you 100 - 150 additional horsepower, but with this, you risk breaking parts.
If setup correctly, you can use nitrous to make some decent power without damaging your engine. With any power adder, it is only when you get carried away adding too much power without beefing up the rest of the engine and drive line when you start breaking parts.
In your case, you do not want to add more than 50 horse power without first installing forged pistions, connecting rods, and crank shaft.
Checkout the Summit Racing Website.
The bang for the buck
Cold Air Intake
Cost = $200 Average. Horsepower gained = 5 HP, and I'm being generous. About $40 per horsepower gained
Nitrous Oxide
Cost = $400 Average. Horsepower gained = 50 HP Average. About $8 per horsepower gained
