That's too small for your GT.
There are quite a few threads on how to turbo a 5SFE... just do a search for 5SFTE.
For one, you're going to need a custom manifold. Then intercooler and piping. All the plumbing for the turbo. Plus fuel upgrades, and then you need a way to tune it.
-Doc
-Dr Tweak, 6GC's resident engine swap wiring expert extraordinaireClick here to see my swapsdrtweak@phoenixtuning.com
hey thaey make a custom adapter that will fit a 3sgte manfold if you want then go on ebay and buy it. it will fit a t3 turbo on it....and plus that turbo does have a t3 plate on it..man trust me your will make some horses but but think of you celica as a saab turbo ...ct26 is ct20 is the way to gooo...or just swap motors