Just to clear up a bit of confusion...
Im the guy selling the kit...
it is the factory kit only available on Alltrac's...
it is considered 'widebody' cause of the widebody appearence it gives...take a look at a real AllTrac and a GTS and the difference is quite apparent...
as far as I know no company/manufacture made or offered an aftermarket widebody kit for the 4th gen Celica as a direct bolt on...
AllTrac's are far and few between so finding a complete kit that came from an AllTrac is incredibly rare...and just for FYI the complete kit is 20+ pieces...I have 3

the IMSA GTO Celica is actually based on the MKIII Celica/Supra platform and the only thing it shares with its production model is the drivetrain layout...front engine rear wheel drive...
In all honesty I feel that the best body kit for the 4th gen came on the 4th gen in the form of the Alltrac model, anything else is gay and rice...
IMSA GTO CELICA INFO
and of course to see comparitive pics of what an AllTrac, GTS and 'hALf-TRAC' looks like - refer to my sig.