There is a way to allow more "ram air". Open up the cover to the air filter and inside there is a square plastic thing at the tip of the box. Inside the square plastic thing is a plate. The plate and the housing for the plate blocks lots of air so remove the little vacuum tube connected to it and remove the plastic square housing. This will allow much more air into the Intake. Also, a simple K&N Air Filter will help too. I'm not talking about the short ram or cold air Intake either. The regular supercharged filter. I noticed an increase in throttle response especially at high speeds.
PS.
If you're wondering what the plastic piece is then read on. When you start you car the plate inside closes to stop air from the outside of your Celica from going into the Intake, and takes the heat from the engine via the opening to the side of the plate inside the plastic housing in order to warm up your engine. Unless you live in Alaska you really do not need to worry about that housing being in there. Assuming, most of you allow your car to warm up for a minute or two you will be fine.
One last note, if you use Synthetic Oil in your vehicle then you definitely do not need that plastic housing in the vehicle. Synthetic Oil in cold temperatures does not get thicker, it stays the same viscosity.