I have seen a GT-Four with flares, but it was a narrowbody ^_^
Just my opinion, but Alltrac/GT-S has so much room to fit giant wheels only a narrow body Celica would really need flares.
Alltrac already suffer from "sunken battleship" wheels, you need some epic gross spacers to fill out any flares I'd think.
Unless you want to run 11"+ wide wheels...?