Get an original airbox. There is a valve just at the airbox where the opening is that you can lift out. THen buy a k&n panel filter. This is the best job for the celica.
The short ram intakes gain about 3-4hp but they will suffer from heat soak and will loose power when the engine is running for awhile. Cold air intake's depends which one you go for. Ebay and injen make gains top end while aem make gains mid end.