Hey, welcome!
Unless you've got a bunch of money, I wouldn't expect to make a whole bunch of power out of your Celica. The Celica isn't known to be a straight line car, but it's alright because it makes up for it in the turns.
That being said, you could easily do intake/headers/exhaust for not too much. But like I said, the strength of the Celica is in the turns. Upgraded sway bars, strut bars, and coilovers/springs would be great suspension mods to stiffen your ride and improve handling. Also don't neglect the less exciting things like tires.
It didn't take me long to figure out that the best bang for your buck when it comes to the Celica is not straight line power mods, but a good suspension set up.
Enjoy!
-Connor
